ラズベリーパイとLCD-USB7XW/BとLCD-USB10XB-T (トラブルシューティング編)

以前の記事『ラズベリーパイとLCD-USB7XW/BとLCD-USB10XB-T (後編: Part 1) 』に、次のコメントをgitlineさんから頂いたので、どうにか解決法を探っていきたいと思います。

gitline 2021年2月18日 23:55

はじめまして。
LCD-USB10XB-Tを入手したので参考にさせていただいております。
突然ですが、どうしても原因がわからず行き詰まっているのでここで質問させていただきます。
本文の通りに、USBモニタ単体での使用、HDMIとUSBモニタの併用のいずれの設定を行った場合も数度はUSBモニタにも出力されるのですが、再起動するとUSBモニタが緑一色の画面に戻ってしまいます。また、このときHDMI出力の方もGUIに入れなくなってしまいます。
動作環境はラズパイ3b+でOSはrasbianを入れています。
当方ラズパイ初心者で勉強中ですので、必要な情報が不足しているかもしれませんが、解決法がもしわかるようであればご教授いただけると幸いです。
よろしくお願いいたします。

返信 削除

手動で設定をする分には問題がなく、でもそこから再起動した場合に何らかの理由でX-Windowsが上手く立ち上がらない様ですが、USBモニタは緑一色表示になるという事なので、udlfbドライバは読み込まれている様です。

なので、この時点では「後編: Part 1」の「ステップ-3: sr_modのモジュールの無効化」までの設定には問題が無いと言えると思います。

ログの確認

こういう場合、Linux系のOSだと、システムのログを確認してみると何かしらのヒントが見つかる事が多いので、ログの確認方を次に。

カーネルメッセージ

コンソール又はターミナル・ウインドウで「display message」という意味の『dmesg』コマンドを使うと起動時以降のLinuxカーネルからのメッセージを確認出来ます:

pi@raspberrypi:~ $ dmesg

X-Windowsで最近のターミナル・ウインドウを使っていると、マウスなどで表示内容を前後にスクロール出来ますが、コンソールの場合では「dmesg」からの出力は1画面に収まらないので「more」コマンドを使って表示をするとモノクロ表示になってしまいますが、1画面に収まる分の内容が表示され、[スペース] キーを押すごとに次の画面へと進んで行くので、コンソール上でも読み易くなります。

pi@raspberrypi:~ $ dmesg | more

又、次の様に「dmesg」コマンドの出力をリダイレクトするとテキストファイルに保存する事も出来ます。

pi@raspberrypi:~ $ dmesg > ~/dmesg-log

なお、保存したファイルを次の様に「more」コマンドで表示すると：

pi@raspberrypi:~ $ more ~/dmesg-log

[スペース] キーで次の画面が表示出来るのに加えて、[b]キー で前の画面に戻る(back)事も出来ます。

因みに、X-Windowsの起動に失敗して画面が真っ黒になってしまった場合だと、キーボード操作をしても反応が無い状態になってしまうかも知れませんが、X-Windowsだけがの起動出来なかった状態であれば、 [Ctrl]+[Alt] を押しながら [F1] キー を押すとバーチャルターミナルに移動できるので、そこで上記のコマンド操作が可能になります。

X-Windows起動時でも同じキー操作をすると、同じくバーチャルターミナルに移動しますが、そこからX-Windowsに戻りたい場合は [Ctrl]+[Alt] を押しながら [F7] キー を押す事で戻る事が出来ます。

例として手持ちのラズベリーパイ(Pi2B)にLCD-USB10XB-Tを繋げて起動した場合のカーネルメッセージを次に張り付けておきます (上下にスクロール可)。

pi@raspberrypi:~ $ dmesg
[    0.000000] Booting Linux on physical CPU 0xf00
[    0.000000] Linux version 4.19.93-v7+ (dom@buildbot) (gcc version 4.9.3 (crosstool-NG crosstool-ng-1.22.0-88-g8460611)) #1290 SMP Fri Jan 10 16:39:50 GMT 2020
[    0.000000] CPU: ARMv7 Processor [410fc075] revision 5 (ARMv7), cr=10c5387d
[    0.000000] CPU: div instructions available: patching division code
[    0.000000] CPU: PIPT / VIPT nonaliasing data cache, VIPT aliasing instruction cache
[    0.000000] OF: fdt: Machine model: Raspberry Pi 2 Model B Rev 1.1
[    0.000000] Memory policy: Data cache writealloc
[    0.000000] cma: Reserved 8 MiB at 0x3ac00000
[    0.000000] On node 0 totalpages: 242688
[    0.000000]   Normal zone: 2133 pages used for memmap
[    0.000000]   Normal zone: 0 pages reserved
[    0.000000]   Normal zone: 242688 pages, LIFO batch:63
[    0.000000] random: get_random_bytes called from start_kernel+0xac/0x4b4 with crng_init=0
[    0.000000] percpu: Embedded 16 pages/cpu s36864 r8192 d20480 u65536
[    0.000000] pcpu-alloc: s36864 r8192 d20480 u65536 alloc=16*4096
[    0.000000] pcpu-alloc: [0] 0 [0] 1 [0] 2 [0] 3
[    0.000000] Built 1 zonelists, mobility grouping on.  Total pages: 240555
[    0.000000] Kernel command line: coherent_pool=1M bcm2708_fb.fbwidth=1920 bcm2708_fb.fbheight=1080 bcm2708_fb.fbswap=1 smsc95xx.macaddr=B8:27:EB:67:87:76 vc_mem.mem_base=0x3ec00000 vc_mem.mem_size=0x40000000  console=ttyAMA0,115200 console=tty1 root=PARTUUID=5e3da3da-02 rootfstype=ext4 elevator=deadline fsck.repair=yes rootwait quiet splash plymouth.ignore-serial-consoles
[    0.000000] Dentry cache hash table entries: 131072 (order: 7, 524288 bytes)
[    0.000000] Inode-cache hash table entries: 65536 (order: 6, 262144 bytes)
[    0.000000] Memory: 939084K/970752K available (8192K kernel code, 653K rwdata, 2220K rodata, 1024K init, 822K bss, 23476K reserved, 8192K cma-reserved)
[    0.000000] Virtual kernel memory layout:
                   vector  : 0xffff0000 - 0xffff1000   (   4 kB)
                   fixmap  : 0xffc00000 - 0xfff00000   (3072 kB)
                   vmalloc : 0xbb800000 - 0xff800000   (1088 MB)
                   lowmem  : 0x80000000 - 0xbb400000   ( 948 MB)
                   modules : 0x7f000000 - 0x80000000   (  16 MB)
                     .text : 0x(ptrval) - 0x(ptrval)   (9184 kB)
                     .init : 0x(ptrval) - 0x(ptrval)   (1024 kB)
                     .data : 0x(ptrval) - 0x(ptrval)   ( 654 kB)
                      .bss : 0x(ptrval) - 0x(ptrval)   ( 823 kB)
[    0.000000] SLUB: HWalign=64, Order=0-3, MinObjects=0, CPUs=4, Nodes=1
[    0.000000] ftrace: allocating 26853 entries in 79 pages
[    0.000000] rcu: Hierarchical RCU implementation.
[    0.000000] NR_IRQS: 16, nr_irqs: 16, preallocated irqs: 16
[    0.000000] arch_timer: cp15 timer(s) running at 19.20MHz (phys).
[    0.000000] clocksource: arch_sys_counter: mask: 0xffffffffffffff max_cycles: 0x46d987e47, max_idle_ns: 440795202767 ns
[    0.000011] sched_clock: 56 bits at 19MHz, resolution 52ns, wraps every 4398046511078ns
[    0.000025] Switching to timer-based delay loop, resolution 52ns
[    0.000359] Console: colour dummy device 80x30
[    0.000383] console [tty1] enabled
[    0.000444] Calibrating delay loop (skipped), value calculated using timer frequency.. 38.40 BogoMIPS (lpj=192000)
[    0.000463] pid_max: default: 32768 minimum: 301
[    0.000902] Mount-cache hash table entries: 2048 (order: 1, 8192 bytes)
[    0.000923] Mountpoint-cache hash table entries: 2048 (order: 1, 8192 bytes)
[    0.002196] CPU: Testing write buffer coherency: ok
[    0.002885] CPU0: update cpu_capacity 1024
[    0.002900] CPU0: thread -1, cpu 0, socket 15, mpidr 80000f00
[    0.003893] Setting up static identity map for 0x100000 - 0x10003c
[    0.004121] rcu: Hierarchical SRCU implementation.
[    0.005310] smp: Bringing up secondary CPUs ...
[    0.006596] CPU1: update cpu_capacity 1024
[    0.006608] CPU1: thread -1, cpu 1, socket 15, mpidr 80000f01
[    0.008051] CPU2: update cpu_capacity 1024
[    0.008063] CPU2: thread -1, cpu 2, socket 15, mpidr 80000f02
[    0.009376] CPU3: update cpu_capacity 1024
[    0.009388] CPU3: thread -1, cpu 3, socket 15, mpidr 80000f03
[    0.009557] smp: Brought up 1 node, 4 CPUs
[    0.009572] SMP: Total of 4 processors activated (153.60 BogoMIPS).
[    0.009578] CPU: All CPU(s) started in HYP mode.
[    0.009584] CPU: Virtualization extensions available.
[    0.010966] devtmpfs: initialized
[    0.026781] VFP support v0.3: implementor 41 architecture 2 part 30 variant 7 rev 5
[    0.027189] clocksource: jiffies: mask: 0xffffffff max_cycles: 0xffffffff, max_idle_ns: 19112604462750000 ns
[    0.027216] futex hash table entries: 1024 (order: 4, 65536 bytes)
[    0.028071] pinctrl core: initialized pinctrl subsystem
[    0.029343] NET: Registered protocol family 16
[    0.033103] DMA: preallocated 1024 KiB pool for atomic coherent allocations
[    0.040667] hw-breakpoint: found 5 (+1 reserved) breakpoint and 4 watchpoint registers.
[    0.040681] hw-breakpoint: maximum watchpoint size is 8 bytes.
[    0.040951] Serial: AMBA PL011 UART driver
[    0.044176] bcm2835-mbox 3f00b880.mailbox: mailbox enabled
[    0.089795] bcm2835-dma 3f007000.dma: DMA legacy API manager at (ptrval), dmachans=0x1
[    0.092077] SCSI subsystem initialized
[    0.092404] usbcore: registered new interface driver usbfs
[    0.092479] usbcore: registered new interface driver hub
[    0.092634] usbcore: registered new device driver usb
[    0.110325] raspberrypi-firmware soc:firmware: Attached to firmware from 2020-01-10 17:01, variant start
[    0.120572] raspberrypi-firmware soc:firmware: Firmware hash is f3e39fed4763ce4efbffabb2d4787aaacddeda0f
[    0.132625] clocksource: Switched to clocksource arch_sys_counter
[    0.235528] VFS: Disk quotas dquot_6.6.0
[    0.235643] VFS: Dquot-cache hash table entries: 1024 (order 0, 4096 bytes)
[    0.235857] FS-Cache: Loaded
[    0.236186] CacheFiles: Loaded
[    0.250653] NET: Registered protocol family 2
[    0.251868] tcp_listen_portaddr_hash hash table entries: 512 (order: 0, 6144 bytes)
[    0.251915] TCP established hash table entries: 8192 (order: 3, 32768 bytes)
[    0.252043] TCP bind hash table entries: 8192 (order: 4, 65536 bytes)
[    0.252231] TCP: Hash tables configured (established 8192 bind 8192)
[    0.252411] UDP hash table entries: 512 (order: 2, 16384 bytes)
[    0.252480] UDP-Lite hash table entries: 512 (order: 2, 16384 bytes)
[    0.252968] NET: Registered protocol family 1
[    0.253830] RPC: Registered named UNIX socket transport module.
[    0.253840] RPC: Registered udp transport module.
[    0.253846] RPC: Registered tcp transport module.
[    0.253853] RPC: Registered tcp NFSv4.1 backchannel transport module.
[    0.256163] hw perfevents: enabled with armv7_cortex_a7 PMU driver, 5 counters available
[    0.260336] Initialise system trusted keyrings
[    0.260667] workingset: timestamp_bits=14 max_order=18 bucket_order=4
[    0.273901] FS-Cache: Netfs 'nfs' registered for caching
[    0.274763] NFS: Registering the id_resolver key type
[    0.274817] Key type id_resolver registered
[    0.274824] Key type id_legacy registered
[    0.274845] nfs4filelayout_init: NFSv4 File Layout Driver Registering...
[    0.278112] Key type asymmetric registered
[    0.278126] Asymmetric key parser 'x509' registered
[    0.278211] Block layer SCSI generic (bsg) driver version 0.4 loaded (major 250)
[    0.278457] io scheduler noop registered
[    0.278468] io scheduler deadline registered (default)
[    0.278745] io scheduler cfq registered
[    0.278758] io scheduler mq-deadline registered (default)
[    0.278767] io scheduler kyber registered
[    0.281342] bcm2708_fb soc:fb: FB found 1 display(s)
[    0.344209] Console: switching to colour frame buffer device 240x67
[    0.380603] bcm2708_fb soc:fb: Registered framebuffer for display 0, size 1920x1080
[    0.383711] bcm2835-rng 3f104000.rng: hwrng registered
[    0.384087] vc-mem: phys_addr:0x00000000 mem_base=0x3ec00000 mem_size:0x40000000(1024 MiB)
[    0.384920] vc-sm: Videocore shared memory driver
[    0.385361] gpiomem-bcm2835 3f200000.gpiomem: Initialised: Registers at 0x3f200000
[    0.402078] brd: module loaded
[    0.417380] loop: module loaded
[    0.418228] Loading iSCSI transport class v2.0-870.
[    0.419258] libphy: Fixed MDIO Bus: probed
[    0.419409] usbcore: registered new interface driver lan78xx
[    0.419500] usbcore: registered new interface driver smsc95xx
[    0.419527] dwc_otg: version 3.00a 10-AUG-2012 (platform bus)
[    0.447494] dwc_otg 3f980000.usb: base=(ptrval)
[    0.647888] Core Release: 2.80a
[    0.647901] Setting default values for core params
[    0.647950] Finished setting default values for core params
[    0.848380] Using Buffer DMA mode
[    0.848390] Periodic Transfer Interrupt Enhancement - disabled
[    0.848397] Multiprocessor Interrupt Enhancement - disabled
[    0.848406] OTG VER PARAM: 0, OTG VER FLAG: 0
[    0.848432] Dedicated Tx FIFOs mode
[    0.849156] WARN::dwc_otg_hcd_init:1045: FIQ DMA bounce buffers: virt = bad14000 dma = 0xfad14000 len=9024
[    0.849194] FIQ FSM acceleration enabled for :
               Non-periodic Split Transactions
               Periodic Split Transactions
               High-Speed Isochronous Endpoints
               Interrupt/Control Split Transaction hack enabled
[    0.849204] dwc_otg: Microframe scheduler enabled
[    0.849287] WARN::hcd_init_fiq:457: FIQ on core 1
[    0.849301] WARN::hcd_init_fiq:458: FIQ ASM at 8067f620 length 36
[    0.849316] WARN::hcd_init_fiq:497: MPHI regs_base at bb810000
[    0.849346] dwc_otg 3f980000.usb: DWC OTG Controller
[    0.849400] dwc_otg 3f980000.usb: new USB bus registered, assigned bus number 1
[    0.849455] dwc_otg 3f980000.usb: irq 56, io mem 0x00000000
[    0.849508] Init: Port Power? op_state=1
[    0.849515] Init: Power Port (0)
[    0.849905] usb usb1: New USB device found, idVendor=1d6b, idProduct=0002, bcdDevice= 4.19
[    0.849921] usb usb1: New USB device strings: Mfr=3, Product=2, SerialNumber=1
[    0.849932] usb usb1: Product: DWC OTG Controller
[    0.849943] usb usb1: Manufacturer: Linux 4.19.93-v7+ dwc_otg_hcd
[    0.849954] usb usb1: SerialNumber: 3f980000.usb
[    0.850920] hub 1-0:1.0: USB hub found
[    0.851005] hub 1-0:1.0: 1 port detected
[    0.851835] dwc_otg: FIQ enabled
[    0.851844] dwc_otg: NAK holdoff enabled
[    0.851850] dwc_otg: FIQ split-transaction FSM enabled
[    0.851865] Module dwc_common_port init
[    0.852284] usbcore: registered new interface driver usb-storage
[    0.852587] mousedev: PS/2 mouse device common for all mice
[    0.853857] bcm2835-wdt bcm2835-wdt: Broadcom BCM2835 watchdog timer
[    0.854164] bcm2835-cpufreq: min=600000 max=900000
[    0.854804] sdhci: Secure Digital Host Controller Interface driver
[    0.854811] sdhci: Copyright(c) Pierre Ossman
[    0.855363] sdhost-bcm2835 3f202000.mmc: could not get clk, deferring probe
[    0.855570] sdhci-pltfm: SDHCI platform and OF driver helper
[    0.856471] ledtrig-cpu: registered to indicate activity on CPUs
[    0.856639] hidraw: raw HID events driver (C) Jiri Kosina
[    0.856907] usbcore: registered new interface driver usbhid
[    0.856914] usbhid: USB HID core driver
[    0.857942] vchiq: vchiq_init_state: slot_zero = (ptrval), is_master = 0
[    0.860058] [vc_sm_connected_init]: start
[    0.870133] [vc_sm_connected_init]: end - returning 0
[    0.871714] Initializing XFRM netlink socket
[    0.871756] NET: Registered protocol family 17
[    0.871925] Key type dns_resolver registered
[    0.872495] Registering SWP/SWPB emulation handler
[    0.873631] registered taskstats version 1
[    0.873658] Loading compiled-in X.509 certificates
[    0.882534] uart-pl011 3f201000.serial: cts_event_workaround enabled
[    0.882792] 3f201000.serial: ttyAMA0 at MMIO 0x3f201000 (irq = 81, base_baud = 0) is a PL011 rev2
[    0.882873] console [ttyAMA0] enabled
[    0.885540] sdhost: log_buf @ (ptrval) (fad13000)
[    0.932636] mmc0: sdhost-bcm2835 loaded - DMA enabled (>1)
[    0.934458] of_cfs_init
[    0.934706] of_cfs_init: OK
[    0.935670] Waiting for root device PARTUUID=5e3da3da-02...
[    0.991377] mmc0: host does not support reading read-only switch, assuming write-enable
[    0.993707] mmc0: new high speed SDXC card at address 0001
[    0.995499] mmcblk0: mmc0:0001 EC2QT 59.6 GiB
[    0.998523]  mmcblk0: p1 p2
[    1.042169] EXT4-fs (mmcblk0p2): mounted filesystem with ordered data mode. Opts: (null)
[    1.042260] VFS: Mounted root (ext4 filesystem) readonly on device 179:2.
[    1.051359] devtmpfs: mounted
[    1.057009] Freeing unused kernel memory: 1024K
[    1.062972] Run /sbin/init as init process
[    1.063131] Indeed it is in host mode hprt0 = 00021501
[    1.143446] random: fast init done
[    1.272714] usb 1-1: new high-speed USB device number 2 using dwc_otg
[    1.272932] Indeed it is in host mode hprt0 = 00001101
[    1.513247] usb 1-1: New USB device found, idVendor=0424, idProduct=9514, bcdDevice= 2.00
[    1.513272] usb 1-1: New USB device strings: Mfr=0, Product=0, SerialNumber=0
[    1.514347] hub 1-1:1.0: USB hub found
[    1.514512] hub 1-1:1.0: 5 ports detected
[    1.717413] systemd[1]: System time before build time, advancing clock.
[    1.832742] usb 1-1.1: new high-speed USB device number 3 using dwc_otg
[    1.873028] NET: Registered protocol family 10
[    1.875011] Segment Routing with IPv6
[    1.945213] systemd[1]: systemd 241 running in system mode. (+PAM +AUDIT +SELINUX +IMA +APPARMOR +SMACK +SYSVINIT +UTMP +LIBCRYPTSETUP +GCRYPT +GNUTLS +ACL +XZ +LZ4 +SECCOMP +BLKID +ELFUTILS +KMOD -IDN2 +IDN -PCRE2 default-hierarchy=hybrid)
[    1.946438] systemd[1]: Detected architecture arm.
[    1.957561] systemd[1]: Set hostname to <raspberrypi>.
[    1.961326] systemd[1]: Failed to bump fs.file-max, ignoring: Invalid argument
[    1.963231] usb 1-1.1: New USB device found, idVendor=0424, idProduct=ec00, bcdDevice= 2.00
[    1.963252] usb 1-1.1: New USB device strings: Mfr=0, Product=0, SerialNumber=0
[    1.966349] smsc95xx v1.0.6
[    2.061587] smsc95xx 1-1.1:1.0 eth0: register 'smsc95xx' at usb-3f980000.usb-1.1, smsc95xx USB 2.0 Ethernet, b8:27:eb:67:87:76
[    2.152814] usb 1-1.2: new high-speed USB device number 4 using dwc_otg
[    2.211846] uart-pl011 3f201000.serial: no DMA platform data
[    2.283322] usb 1-1.2: New USB device found, idVendor=0409, idProduct=005a, bcdDevice= 1.00
[    2.283347] usb 1-1.2: New USB device strings: Mfr=0, Product=0, SerialNumber=0
[    2.284334] hub 1-1.2:1.0: USB hub found
[    2.284467] hub 1-1.2:1.0: 4 ports detected
[    2.382839] usb 1-1.3: new high-speed USB device number 5 using dwc_otg
[    2.524223] usb 1-1.3: New USB device found, idVendor=05e3, idProduct=0610, bcdDevice= 4.02
[    2.524246] usb 1-1.3: New USB device strings: Mfr=1, Product=2, SerialNumber=0
[    2.524259] usb 1-1.3: Product: USB2.0 Hub
[    2.524271] usb 1-1.3: Manufacturer: GenesysLogic
[    2.525694] hub 1-1.3:1.0: USB hub found
[    2.526955] hub 1-1.3:1.0: 4 ports detected
[    2.612707] usb 1-1.2.3: new high-speed USB device number 6 using dwc_otg
[    2.747592] usb 1-1.2.3: New USB device found, idVendor=17e9, idProduct=0156, bcdDevice= 1.33
[    2.747616] usb 1-1.2.3: New USB device strings: Mfr=1, Product=2, SerialNumber=3
[    2.747629] usb 1-1.2.3: Product: I-O DATA LCD-USB10XT
[    2.747642] usb 1-1.2.3: Manufacturer: DisplayLink
[    2.747653] usb 1-1.2.3: SerialNumber: 100▮▮▮▮▮
[    2.804052] usb-storage 1-1.2.3:2.0: USB Mass Storage device detected
[    2.805631] scsi host0: usb-storage 1-1.2.3:2.0
[    2.842725] usb 1-1.4: new low-speed USB device number 7 using dwc_otg
[    2.993809] usb 1-1.4: New USB device found, idVendor=046d, idProduct=c31c, bcdDevice=64.02
[    2.993835] usb 1-1.4: New USB device strings: Mfr=1, Product=2, SerialNumber=0
[    2.993846] usb 1-1.4: Product: USB Keyboard
[    2.993858] usb 1-1.4: Manufacturer: Logitech
[    3.016884] input: Logitech USB Keyboard as /devices/platform/soc/3f980000.usb/usb1/1-1/1-1.4/1-1.4:1.0/0003:046D:C31C.0001/input/input0
[    3.072717] usb 1-1.2.4: new full-speed USB device number 8 using dwc_otg
[    3.083867] hid-generic 0003:046D:C31C.0001: input,hidraw0: USB HID v1.10 Keyboard [Logitech USB Keyboard] on usb-3f980000.usb-1.4/input0
[    3.118166] input: Logitech USB Keyboard Consumer Control as /devices/platform/soc/3f980000.usb/usb1/1-1/1-1.4/1-1.4:1.1/0003:046D:C31C.0002/input/input1
[    3.183044] input: Logitech USB Keyboard System Control as /devices/platform/soc/3f980000.usb/usb1/1-1/1-1.4/1-1.4:1.1/0003:046D:C31C.0002/input/input2
[    3.183753] hid-generic 0003:046D:C31C.0002: input,hiddev96,hidraw1: USB HID v1.10 Device [Logitech USB Keyboard] on usb-3f980000.usb-1.4/input1
[    3.207680] random: systemd: uninitialized urandom read (16 bytes read)
[    3.210296] usb 1-1.2.4: New USB device found, idVendor=0eef, idProduct=0001, bcdDevice= 1.00
[    3.210317] usb 1-1.2.4: New USB device strings: Mfr=1, Product=2, SerialNumber=0
[    3.210329] usb 1-1.2.4: Product: USB TouchController
[    3.210341] usb 1-1.2.4: Manufacturer: eGalax Inc.
[    3.220236] input: eGalax Inc. USB TouchController as /devices/platform/soc/3f980000.usb/usb1/1-1/1-1.2/1-1.2.4/1-1.2.4:1.0/0003:0EEF:0001.0003/input/input3
[    3.220850] input: eGalax Inc. USB TouchController Touchscreen as /devices/platform/soc/3f980000.usb/usb1/1-1/1-1.2/1-1.2.4/1-1.2.4:1.0/0003:0EEF:0001.0003/input/input4
[    3.221322] hid-generic 0003:0EEF:0001.0003: input,hidraw2: USB HID v2.10 Pointer [eGalax Inc. USB TouchController] on usb-3f980000.usb-1.2.4/input0
[    3.224842] random: systemd: uninitialized urandom read (16 bytes read)
[    3.225700] systemd[1]: Listening on udev Kernel Socket.
[    3.227321] random: systemd: uninitialized urandom read (16 bytes read)
[    3.228266] systemd[1]: Set up automount Arbitrary Executable File Formats File System Automount Point.
[    3.237479] systemd[1]: Listening on Syslog Socket.
[    3.243842] systemd[1]: Created slice User and Session Slice.
[    3.248274] systemd[1]: Created slice system-getty.slice.
[    3.249455] systemd[1]: Listening on Journal Socket (/dev/log).
[    3.302737] usb 1-1.5: new low-speed USB device number 9 using dwc_otg
[    3.446419] usb 1-1.5: New USB device found, idVendor=046d, idProduct=c077, bcdDevice=72.00
[    3.446447] usb 1-1.5: New USB device strings: Mfr=1, Product=2, SerialNumber=0
[    3.446460] usb 1-1.5: Product: USB Optical Mouse
[    3.446474] usb 1-1.5: Manufacturer: Logitech
[    3.454223] input: Logitech USB Optical Mouse as /devices/platform/soc/3f980000.usb/usb1/1-1/1-1.5/1-1.5:1.0/0003:046D:C077.0004/input/input5
[    3.455065] hid-generic 0003:046D:C077.0004: input,hidraw3: USB HID v1.11 Mouse [Logitech USB Optical Mouse] on usb-3f980000.usb-1.5/input0
[    3.617228] i2c /dev entries driver
[    3.835096] scsi host0: scsi scan: INQUIRY result too short (5), using 36
[    3.835133] scsi 0:0:0:0: CD-ROM                                           PQ: 0 ANSI: 0
[    4.335360] EXT4-fs (mmcblk0p2): re-mounted. Opts: (null)
[    4.491060] systemd-journald[107]: Received request to flush runtime journal from PID 1
[    6.068254] scsi 0:0:0:0: Attached scsi generic sg0 type 5
[    6.414776] vc_sm_cma: module is from the staging directory, the quality is unknown, you have been warned.
[    6.418419] bcm2835_vc_sm_cma_probe: Videocore shared memory driver
[    6.418447] [vc_sm_connected_init]: start
[    6.421812] media: Linux media interface: v0.10
[    6.430828] [vc_sm_connected_init]: installed successfully
[    6.501962] videodev: Linux video capture interface: v2.00
[    6.564345] bcm2835_mmal_vchiq: module is from the staging directory, the quality is unknown, you have been warned.
[    6.633100] bcm2835_v4l2: module is from the staging directory, the quality is unknown, you have been warned.
[    6.646705] bcm2835_codec: module is from the staging directory, the quality is unknown, you have been warned.
[    6.685569] input: soc:shutdown_button as /devices/platform/soc/soc:shutdown_button/input/input6
[    6.692027] bcm2835-codec bcm2835-codec: Device registered as /dev/video10
[    6.692126] bcm2835-codec bcm2835-codec: Loaded V4L2 decode
[    6.715529] snd_bcm2835: module is from the staging directory, the quality is unknown, you have been warned.
[    6.718978] bcm2835-codec bcm2835-codec: Device registered as /dev/video11
[    6.719038] bcm2835-codec bcm2835-codec: Loaded V4L2 encode
[    6.728776] bcm2835-codec bcm2835-codec: Device registered as /dev/video12
[    6.728844] bcm2835-codec bcm2835-codec: Loaded V4L2 isp
[    6.803452] bcm2835_audio soc:audio: card created with 8 channels
[    7.135029] usbcore: registered new interface driver usbtouchscreen
[    7.997285] usbcore: registered new interface driver uas
[   10.185916] random: crng init done
[   10.185948] random: 7 urandom warning(s) missed due to ratelimiting
[   10.480039] 8021q: 802.1Q VLAN Support v1.8
[   10.734784] cfg80211: Loading compiled-in X.509 certificates for regulatory database
[   10.961235] Adding 102396k swap on /var/swap.  Priority:-2 extents:1 across:102396k SSFS
[   11.007862] cfg80211: Loaded X.509 cert 'sforshee: 00b28ddf47aef9cea7'
[   11.398851] smsc95xx 1-1.1:1.0 eth0: hardware isn't capable of remote wakeup
[   12.343832] udlfb 1-1.2.3:1.0: vendor descriptor length: 23 data: 17 5f 01 00 15 05 00 01 03 00 04
[   12.343866] udlfb 1-1.2.3:1.0: DL chip limited to 700000 pixel modes
[   12.409401] usb 1-1.2.3: fb1 is DisplayLink USB device (1024x600, 2400K framebuffer memory)
[   12.409802] usbcore: registered new interface driver udlfb
[   12.622586] usbcore: registered new interface driver udl
[   12.986373] smsc95xx 1-1.1:1.0 eth0: link up, 100Mbps, full-duplex, lpa 0xCDE1
[   19.038614] fuse init (API version 7.27)

1年前からアップデートをしていないシステム(Linux 4.19.93-v7)のログなのと、同じシステムでも毎起動ごとにログされる内容の順番が微妙に違ったりするので、全く同じログが保存されている可能性は低いと思いますが、正常起動時のログとして比較すると、ログされているエラーの発見の参考になるかと思います。 (可能であれば、同じシステムでUSB-LCD接続時と非接続時で比較する事もお勧めします。)

上のログでは、カーネルのタイムスタンプが[　1.963231]秒の「usb 1-1.1: New USB device found, idVendor=0424, idProduct=ec00, bcdDevice= 2.00」とある行からUSB接続のデバイスの設定が始まっていて、LCD-USB10XB-Tは[　2.747629]秒の行で発見されています。

又、後の方で、udlfドライバーが[　12.343832]秒で読み込まれています。

Xサーバーログ

X-Windowsのサーバー、Xorgのログは /var/log/Xorg.0.log のファイルに出力されます。

X-Windowsの起動に失敗した場合、バーチャルコンソールでログを確認する事も可能ですが、USB-LCDを外して以前起動出来た状態にしてX-Windowsに再起動し直すと、失敗した前回のログは/var/log/Xorg.0.log.oldで確認する事も出来ます。

次にカーネルメッセージログ同様に、手持ちのPi2BにLCD-USB10XB-Tを繋げて立ち上げた場合の /var/log/Xorg の内容を張り付けておきます (上下にスクロール可)

[    12.706]
X.Org X Server 1.20.4
X Protocol Version 11, Revision 0
[    12.707] Build Operating System: Linux 4.15.0-48-generic armv8l Raspbian
[    12.707] Current Operating System: Linux raspberrypi 4.19.93-v7+ #1290 SMP Fri Jan 10 16:39:50 GMT 2020 armv7l
[    12.707] Kernel command line: coherent_pool=1M bcm2708_fb.fbwidth=1920 bcm2708_fb.fbheight=1080 bcm2708_fb.fbswap=1 smsc95xx.macaddr=B8:27:EB:67:87:76 vc_mem.mem_base=0x3ec00000 vc_mem.mem_size=0x40000000  console=ttyAMA0,115200 console=tty1 root=PARTUUID=5e3da3da-02 rootfstype=ext4 elevator=deadline fsck.repair=yes rootwait quiet splash plymouth.ignore-serial-consoles
[    12.708] Build Date: 05 June 2019  12:49:54PM
[    12.708] xorg-server 2:1.20.4-1+rpt1 (https://www.debian.org/support)
[    12.708] Current version of pixman: 0.36.0
[    12.708]     Before reporting problems, check http://wiki.x.org
    to make sure that you have the latest version.
[    12.708] Markers: (--) probed, (**) from config file, (==) default setting,
    (++) from command line, (!!) notice, (II) informational,
    (WW) warning, (EE) error, (NI) not implemented, (??) unknown.
[    12.709] (==) Log file: "/var/log/Xorg.0.log", Time: Sun Feb 21 00:09:29 2021
[    12.713] (==) Using system config directory "/usr/share/X11/xorg.conf.d"
[    12.718] (==) ServerLayout "default"
[    12.718] (**) |-->Screen "primary" (0)
[    12.718] (**) |   |-->Monitor "lcd-monitor"
[    12.725] (**) |   |-->Device "RPi HDMI"
[    12.725] (**) |-->Screen "secondary" (1)
[    12.725] (**) |   |-->Monitor "usb-lcd"
[    12.727] (**) |   |-->Device "Displaylink"
[    12.727] (==) Automatically adding devices
[    12.728] (==) Automatically enabling devices
[    12.728] (==) Automatically adding GPU devices
[    12.728] (==) Max clients allowed: 256, resource mask: 0x1fffff
[    12.728] (WW) The directory "/usr/share/fonts/X11/misc" does not exist.
[    12.728]     Entry deleted from font path.
[    12.728] (WW) The directory "/usr/share/fonts/X11/cyrillic" does not exist.
[    12.728]     Entry deleted from font path.
[    12.730] (WW) The directory "/usr/share/fonts/X11/75dpi/" does not exist.
[    12.730]     Entry deleted from font path.
[    12.730] (WW) The directory "/usr/share/fonts/X11/Type1" does not exist.
[    12.730]     Entry deleted from font path.
[    12.730] (WW) The directory "/usr/share/fonts/X11/75dpi" does not exist.
[    12.730]     Entry deleted from font path.
[    12.730] (==) FontPath set to:
    /usr/share/fonts/X11/100dpi/:unscaled,
    /usr/share/fonts/X11/100dpi,
    built-ins
[    12.730] (==) ModulePath set to "/usr/lib/xorg/modules"
[    12.730] (II) The server relies on udev to provide the list of input devices.
    If no devices become available, reconfigure udev or disable AutoAddDevices.
[    12.730] (II) Loader magic: 0x1fcf80
[    12.730] (II) Module ABI versions:
[    12.730]     X.Org ANSI C Emulation: 0.4
[    12.730]     X.Org Video Driver: 24.0
[    12.730]     X.Org XInput driver : 24.1
[    12.731]     X.Org Server Extension : 10.0
[    12.734] (++) using VT number 7

[    12.735] (II) systemd-logind: logind integration requires -keeptty and -keeptty was not provided, disabling logind integration
[    12.735] (II) no primary bus or device found
[    12.736] (II) LoadModule: "glx"
[    12.741] (II) Loading /usr/lib/xorg/modules/extensions/libglx.so
[    12.818] (II) Module glx: vendor="X.Org Foundation"
[    12.819]     compiled for 1.20.4, module version = 1.0.0
[    12.819]     ABI class: X.Org Server Extension, version 10.0
[    12.819] (II) LoadModule: "fbturbo"
[    12.819] (II) Loading /usr/lib/xorg/modules/drivers/fbturbo_drv.so
[    12.824] (II) Module fbturbo: vendor="X.Org Foundation"
[    12.824]     compiled for 1.20.3, module version = 0.5.1
[    12.824]     Module class: X.Org Video Driver
[    12.825]     ABI class: X.Org Video Driver, version 24.0
[    12.825] (II) FBTURBO: driver for framebuffer: fbturbo
[    12.855] (WW) Falling back to old probe method for fbturbo
[    12.855] (II) Loading sub module "fbdevhw"
[    12.855] (II) LoadModule: "fbdevhw"
[    12.856] (II) Loading /usr/lib/xorg/modules/libfbdevhw.so
[    12.860] (II) Module fbdevhw: vendor="X.Org Foundation"
[    12.860]     compiled for 1.20.4, module version = 0.0.2
[    12.860]     ABI class: X.Org Video Driver, version 24.0
[    12.860] (II) FBTURBO(0): using /dev/fb0
[    12.861] (II) FBTURBO(1): using /dev/fb1
[    12.861] (WW) VGA arbiter: cannot open kernel arbiter, no multi-card support
[    12.861] (II) FBTURBO(0): Creating default Display subsection in Screen section
    "primary" for depth/fbbpp 24/32
[    12.861] (==) FBTURBO(0): Depth 24, (==) framebuffer bpp 32
[    12.862] (==) FBTURBO(0): RGB weight 888
[    12.862] (==) FBTURBO(0): Default visual is TrueColor
[    12.862] (==) FBTURBO(0): Using gamma correction (1.0, 1.0, 1.0)
[    12.862] (II) FBTURBO(0): hardware: BCM2708 FB (video memory: 8100kB)
[    12.862] (DB) xf86MergeOutputClassOptions unsupported bus type 0
[    12.862] (**) FBTURBO(0): Option "fbdev" "/dev/fb0"
[    12.862] (**) FBTURBO(0): Option "SwapbuffersWait" "true"
[    12.863] (II) FBTURBO(0): processor: ARM Cortex-A7
[    12.863] (II) FBTURBO(0): checking modes against framebuffer device...
[    12.863] (II) FBTURBO(0): checking modes against monitor...
[    12.863] (II) FBTURBO(0): Virtual size is 1920x1080 (pitch 1920)
[    12.863] (**) FBTURBO(0):  Built-in mode "current"
[    12.863] (==) FBTURBO(0): DPI set to (96, 96)
[    12.863] (II) Loading sub module "fb"
[    12.863] (II) LoadModule: "fb"
[    12.864] (II) Loading /usr/lib/xorg/modules/libfb.so
[    12.871] (II) Module fb: vendor="X.Org Foundation"
[    12.871]     compiled for 1.20.4, module version = 1.0.0
[    12.871]     ABI class: X.Org ANSI C Emulation, version 0.4
[    12.872] (II) FBTURBO(1): Creating default Display subsection in Screen section
    "secondary" for depth/fbbpp 16/16
[    12.872] (==) FBTURBO(1): Depth 16, (==) framebuffer bpp 16
[    12.872] (==) FBTURBO(1): RGB weight 565
[    12.872] (==) FBTURBO(1): Default visual is TrueColor
[    12.872] (==) FBTURBO(1): Using gamma correction (1.0, 1.0, 1.0)
[    12.872] (II) FBTURBO(1): hardware: udlfb (video memory: 1200kB)
[    12.872] (DB) xf86MergeOutputClassOptions unsupported bus type 0
[    12.872] (**) FBTURBO(1): Option "fbdev" "/dev/fb1"
[    12.872] (**) FBTURBO(1): Option "SwapbuffersWait" "true"
[    12.873] (II) FBTURBO(1): processor: ARM Cortex-A7
[    12.873] (II) FBTURBO(1): checking modes against framebuffer device...
[    12.873] (II) FBTURBO(1): checking modes against monitor...
[    12.873] (II) FBTURBO(1): Virtual size is 1024x600 (pitch 1024)
[    12.873] (**) FBTURBO(1):  Built-in mode "current": 49.0 MHz, 37.3 kHz, 59.9 Hz
[    12.873] (II) FBTURBO(1): Modeline "current"x0.0   49.00  1024 1064 1168 1312  600 603 613 624 +hsync +vsync -csync (37.3 kHz b)
[    12.873] (==) FBTURBO(1): DPI set to (96, 96)
[    12.873] (II) Loading sub module "fb"
[    12.873] (II) LoadModule: "fb"
[    12.874] (II) Loading /usr/lib/xorg/modules/libfb.so
[    12.874] (II) Module fb: vendor="X.Org Foundation"
[    12.874]     compiled for 1.20.4, module version = 1.0.0
[    12.874]     ABI class: X.Org ANSI C Emulation, version 0.4
[    12.894] (II) FBTURBO(0): using backing store heuristics
[    12.912] (II) FBTURBO(0): can't load 'g2d_23' kernel module
[    12.912] (II) FBTURBO(0): failed to enable the use of sunxi display controller
[    12.912] (II) FBTURBO(0): No sunxi-g2d hardware detected (check /dev/disp and /dev/g2d)
[    12.912] (II) FBTURBO(0): G2D hardware acceleration can't be enabled
[    12.912] (II) FBTURBO(0): enabled fbdev copyarea acceleration
[    12.913] (==) FBTURBO(0): Backing store enabled
[    12.923] (==) FBTURBO(0): DPMS enabled
[    12.923] (II) FBTURBO(0): failed to enable hardware cursor
[    12.923] (II) FBTURBO(0): no 3D acceleration because the driver has been compiled without libUMP
[    12.923] (II) FBTURBO(0): if this is wrong and needs to be fixed, please check ./configure log
[    12.925] (II) FBTURBO(1): using backing store heuristics
[    12.942] (II) FBTURBO(1): can't load 'g2d_23' kernel module
[    12.943] (II) FBTURBO(1): failed to enable the use of sunxi display controller
[    12.943] (II) FBTURBO(1): No sunxi-g2d hardware detected (check /dev/disp and /dev/g2d)
[    12.943] (II) FBTURBO(1): G2D hardware acceleration can't be enabled
[    12.943] (II) FBTURBO(1): enabled VFP/NEON optimizations
[    12.943] (==) FBTURBO(1): Backing store enabled
[    12.944] (==) FBTURBO(1): DPMS enabled
[    12.944] (II) FBTURBO(1): failed to enable hardware cursor
[    12.944] (II) FBTURBO(1): no 3D acceleration because the driver has been compiled without libUMP
[    12.944] (II) FBTURBO(1): if this is wrong and needs to be fixed, please check ./configure log
[    12.944] (II) Initializing extension Generic Event Extension
[    12.945] (II) Initializing extension SHAPE
[    12.947] (II) Initializing extension MIT-SHM
[    12.949] (II) Initializing extension XInputExtension
[    12.955] (II) Initializing extension XTEST
[    12.958] (II) Initializing extension BIG-REQUESTS
[    12.960] (II) Initializing extension SYNC
[    12.962] (II) Initializing extension XKEYBOARD
[    12.965] (II) Initializing extension XC-MISC
[    12.967] (II) Initializing extension SECURITY
[    12.970] (II) Initializing extension XFIXES
[    12.972] (II) Initializing extension RENDER
[    12.975] (II) Initializing extension RANDR
[    12.977] (II) Initializing extension COMPOSITE
[    12.979] (II) Initializing extension DAMAGE
[    12.983] (II) Initializing extension MIT-SCREEN-SAVER
[    12.985] (II) Initializing extension DOUBLE-BUFFER
[    12.991] (II) Initializing extension RECORD
[    12.994] (II) Initializing extension DPMS
[    12.997] (II) Initializing extension Present
[    12.999] (II) Initializing extension DRI3
[    12.999] (II) Initializing extension X-Resource
[    13.002] (II) Initializing extension XVideo
[    13.004] (II) Initializing extension XVideo-MotionCompensation
[    13.004] (II) Initializing extension SELinux
[    13.004] (II) SELinux: Disabled on system
[    13.004] (II) Initializing extension GLX
[    13.009] (II) AIGLX: Screen 0 is not DRI2 capable
[    14.740] (II) IGLX: Loaded and initialized swrast
[    14.740] (II) GLX: Initialized DRISWRAST GL provider for screen 0
[    14.740] (II) AIGLX: Screen 1 is not DRI2 capable
[    14.771] (II) IGLX: Loaded and initialized swrast
[    14.771] (II) GLX: Initialized DRISWRAST GL provider for screen 1
[    14.772] (II) Initializing extension XFree86-VidModeExtension
[    14.774] (II) Initializing extension XFree86-DGA
[    14.777] (II) Initializing extension XFree86-DRI
[    14.780] (II) Initializing extension DRI2
[    15.153] (II) config/udev: Adding input device eGalax Inc. USB TouchController (/dev/input/event3)
[    15.154] (**) eGalax Inc. USB TouchController: Applying InputClass "libinput pointer catchall"
[    15.154] (II) LoadModule: "libinput"
[    15.154] (II) Loading /usr/lib/xorg/modules/input/libinput_drv.so
[    15.199] (II) Module libinput: vendor="X.Org Foundation"
[    15.199]     compiled for 1.20.3, module version = 0.28.2
[    15.199]     Module class: X.Org XInput Driver
[    15.199]     ABI class: X.Org XInput driver, version 24.1
[    15.199] (II) Using input driver 'libinput' for 'eGalax Inc. USB TouchController'
[    15.199] (**) eGalax Inc. USB TouchController: always reports core events
[    15.199] (**) Option "Device" "/dev/input/event3"
[    15.199] (**) Option "_source" "server/udev"
[    15.254] (II) event3  - eGalax Inc. USB TouchController: is tagged by udev as: Mouse
[    15.256] (II) event3  - eGalax Inc. USB TouchController: device is a pointer
[    15.257] (II) event3  - eGalax Inc. USB TouchController: device removed
[    15.290] (**) Option "config_info" "udev:/sys/devices/platform/soc/3f980000.usb/usb1/1-1/1-1.2/1-1.2.4/1-1.2.4:1.0/0003:0EEF:0001.0003/input/input3/event3"
[    15.291] (II) XINPUT: Adding extended input device "eGalax Inc. USB TouchController" (type: MOUSE, id 6)
[    15.292] (**) Option "AccelerationScheme" "none"
[    15.292] (**) eGalax Inc. USB TouchController: (accel) selected scheme none/0
[    15.292] (**) eGalax Inc. USB TouchController: (accel) acceleration factor: 2.000
[    15.292] (**) eGalax Inc. USB TouchController: (accel) acceleration threshold: 4
[    15.306] (II) event3  - eGalax Inc. USB TouchController: is tagged by udev as: Mouse
[    15.309] (II) event3  - eGalax Inc. USB TouchController: device is a pointer
[    15.316] (II) config/udev: Adding input device eGalax Inc. USB TouchController (/dev/input/js0)
[    15.316] (II) No input driver specified, ignoring this device.
[    15.316] (II) This device may have been added with another device file.
[    15.322] (II) config/udev: Adding input device eGalax Inc. USB TouchController (/dev/input/mouse0)
[    15.322] (II) No input driver specified, ignoring this device.
[    15.322] (II) This device may have been added with another device file.
[    15.328] (II) config/udev: Adding input device eGalax Inc. USB TouchController Touchscreen (/dev/input/event4)
[    15.328] (**) eGalax Inc. USB TouchController Touchscreen: Applying InputClass "libinput tablet catchall"
[    15.328] (II) Using input driver 'libinput' for 'eGalax Inc. USB TouchController Touchscreen'
[    15.328] (**) eGalax Inc. USB TouchController Touchscreen: always reports core events
[    15.328] (**) Option "Device" "/dev/input/event4"
[    15.329] (**) Option "_source" "server/udev"
[    15.343] (II) event4  - eGalax Inc. USB TouchController Touchscreen: is tagged by udev as: Tablet
[    15.345] (EE) event4  - eGalax Inc. USB TouchController Touchscreen: libinput bug: missing tablet capabilities: btn-stylus resolution. Ignoring this device.
[    15.345] (II) event4  - eGalax Inc. USB TouchController Touchscreen: device is a tablet
[    15.390] (II) event4  - failed to create input device '/dev/input/event4'.
[    15.391] (EE) libinput: eGalax Inc. USB TouchController Touchscreen: Failed to create a device for /dev/input/event4
[    15.391] (EE) PreInit returned 2 for "eGalax Inc. USB TouchController Touchscreen"
[    15.391] (II) UnloadModule: "libinput"
[    15.397] (II) config/udev: Adding input device eGalax Inc. USB TouchController Touchscreen (/dev/input/mouse1)
[    15.397] (II) No input driver specified, ignoring this device.
[    15.397] (II) This device may have been added with another device file.
[    15.403] (II) config/udev: Adding input device Logitech USB Keyboard (/dev/input/event0)
[    15.403] (**) Logitech USB Keyboard: Applying InputClass "libinput keyboard catchall"
[    15.403] (II) Using input driver 'libinput' for 'Logitech USB Keyboard'
[    15.403] (**) Logitech USB Keyboard: always reports core events
[    15.404] (**) Option "Device" "/dev/input/event0"
[    15.404] (**) Option "_source" "server/udev"
[    15.417] (II) event0  - Logitech USB Keyboard: is tagged by udev as: Keyboard
[    15.417] (II) event0  - Logitech USB Keyboard: device is a keyboard
[    15.418] (II) event0  - Logitech USB Keyboard: device removed
[    15.450] (**) Option "config_info" "udev:/sys/devices/platform/soc/3f980000.usb/usb1/1-1/1-1.4/1-1.4:1.0/0003:046D:C31C.0001/input/input0/event0"
[    15.450] (II) XINPUT: Adding extended input device "Logitech USB Keyboard" (type: KEYBOARD, id 7)
[    15.450] (**) Option "xkb_model" "pc105"
[    15.450] (**) Option "xkb_layout" "us"
[    15.465] (II) event0  - Logitech USB Keyboard: is tagged by udev as: Keyboard
[    15.465] (II) event0  - Logitech USB Keyboard: device is a keyboard
[    15.473] (II) config/udev: Adding input device Logitech USB Keyboard Consumer Control (/dev/input/event1)
[    15.473] (**) Logitech USB Keyboard Consumer Control: Applying InputClass "libinput keyboard catchall"
[    15.473] (II) Using input driver 'libinput' for 'Logitech USB Keyboard Consumer Control'
[    15.473] (**) Logitech USB Keyboard Consumer Control: always reports core events
[    15.473] (**) Option "Device" "/dev/input/event1"
[    15.473] (**) Option "_source" "server/udev"
[    15.487] (II) event1  - Logitech USB Keyboard Consumer Control: is tagged by udev as: Keyboard
[    15.487] (II) event1  - Logitech USB Keyboard Consumer Control: device is a keyboard
[    15.488] (II) event1  - Logitech USB Keyboard Consumer Control: device removed
[    15.521] (**) Option "config_info" "udev:/sys/devices/platform/soc/3f980000.usb/usb1/1-1/1-1.4/1-1.4:1.1/0003:046D:C31C.0002/input/input1/event1"
[    15.521] (II) XINPUT: Adding extended input device "Logitech USB Keyboard Consumer Control" (type: KEYBOARD, id 8)
[    15.521] (**) Option "xkb_model" "pc105"
[    15.521] (**) Option "xkb_layout" "us"
[    15.543] (II) event1  - Logitech USB Keyboard Consumer Control: is tagged by udev as: Keyboard
[    15.543] (II) event1  - Logitech USB Keyboard Consumer Control: device is a keyboard
[    15.554] (II) config/udev: Adding input device Logitech USB Keyboard System Control (/dev/input/event2)
[    15.554] (**) Logitech USB Keyboard System Control: Applying InputClass "libinput keyboard catchall"
[    15.554] (II) Using input driver 'libinput' for 'Logitech USB Keyboard System Control'
[    15.554] (**) Logitech USB Keyboard System Control: always reports core events
[    15.554] (**) Option "Device" "/dev/input/event2"
[    15.555] (**) Option "_source" "server/udev"
[    15.575] (II) event2  - Logitech USB Keyboard System Control: is tagged by udev as: Keyboard
[    15.575] (II) event2  - Logitech USB Keyboard System Control: device is a keyboard
[    15.576] (II) event2  - Logitech USB Keyboard System Control: device removed
[    15.620] (**) Option "config_info" "udev:/sys/devices/platform/soc/3f980000.usb/usb1/1-1/1-1.4/1-1.4:1.1/0003:046D:C31C.0002/input/input2/event2"
[    15.620] (II) XINPUT: Adding extended input device "Logitech USB Keyboard System Control" (type: KEYBOARD, id 9)
[    15.620] (**) Option "xkb_model" "pc105"
[    15.620] (**) Option "xkb_layout" "us"
[    15.635] (II) event2  - Logitech USB Keyboard System Control: is tagged by udev as: Keyboard
[    15.635] (II) event2  - Logitech USB Keyboard System Control: device is a keyboard
[    15.642] (II) config/udev: Adding input device Logitech USB Optical Mouse (/dev/input/event5)
[    15.642] (**) Logitech USB Optical Mouse: Applying InputClass "libinput pointer catchall"
[    15.643] (II) Using input driver 'libinput' for 'Logitech USB Optical Mouse'
[    15.643] (**) Logitech USB Optical Mouse: always reports core events
[    15.643] (**) Option "Device" "/dev/input/event5"
[    15.643] (**) Option "_source" "server/udev"
[    15.656] (II) event5  - Logitech USB Optical Mouse: is tagged by udev as: Mouse
[    15.657] (II) event5  - Logitech USB Optical Mouse: device is a pointer
[    15.657] (II) event5  - Logitech USB Optical Mouse: device removed
[    15.700] (**) Option "config_info" "udev:/sys/devices/platform/soc/3f980000.usb/usb1/1-1/1-1.5/1-1.5:1.0/0003:046D:C077.0004/input/input5/event5"
[    15.700] (II) XINPUT: Adding extended input device "Logitech USB Optical Mouse" (type: MOUSE, id 10)
[    15.701] (**) Option "AccelerationScheme" "none"
[    15.701] (**) Logitech USB Optical Mouse: (accel) selected scheme none/0
[    15.702] (**) Logitech USB Optical Mouse: (accel) acceleration factor: 2.000
[    15.702] (**) Logitech USB Optical Mouse: (accel) acceleration threshold: 4
[    15.715] (II) event5  - Logitech USB Optical Mouse: is tagged by udev as: Mouse
[    15.716] (II) event5  - Logitech USB Optical Mouse: device is a pointer
[    15.722] (II) config/udev: Adding input device Logitech USB Optical Mouse (/dev/input/mouse2)
[    15.722] (II) No input driver specified, ignoring this device.
[    15.722] (II) This device may have been added with another device file.
[    15.726] (II) config/udev: Adding input device soc:shutdown_button (/dev/input/event6)
[    15.726] (**) soc:shutdown_button: Applying InputClass "libinput keyboard catchall"
[    15.726] (II) Using input driver 'libinput' for 'soc:shutdown_button'
[    15.726] (**) soc:shutdown_button: always reports core events
[    15.726] (**) Option "Device" "/dev/input/event6"
[    15.726] (**) Option "_source" "server/udev"
[    15.733] (II) event6  - soc:shutdown_button: is tagged by udev as: Keyboard
[    15.733] (II) event6  - soc:shutdown_button: device is a keyboard
[    15.734] (II) event6  - soc:shutdown_button: device removed
[    15.780] (**) Option "config_info" "udev:/sys/devices/platform/soc/soc:shutdown_button/input/input6/event6"
[    15.780] (II) XINPUT: Adding extended input device "soc:shutdown_button" (type: KEYBOARD, id 11)
[    15.780] (**) Option "xkb_model" "pc105"
[    15.780] (**) Option "xkb_layout" "us"
[    15.788] (II) event6  - soc:shutdown_button: is tagged by udev as: Keyboard
[    15.788] (II) event6  - soc:shutdown_button: device is a keyboard

ログからの考察

もしも、gitlineさんからカーネルメッセージとXサーバーのログを(多分可能だと思うので)コメント欄経由でUPしてもらえたらここでログを比較してみたいかと思います。

続く。

[続き: 21/Mar/2021 追記] ログからの考察

まずgitlineさんがGoogleドキュメントに上げてくれたログのLCD-USBに出力が表示されない時のカーネルメッセージを次に:

[    0.000000] Booting Linux on physical CPU 0x0
[    0.000000] Linux version 5.4.83-v7+ (dom@buildbot) (gcc version 8.4.0 (Ubuntu/Linaro 8.4.0-3ubuntu1)) #1379 SMP Mon Dec 14 13:08:57 GMT 2020
[    0.000000] CPU: ARMv7 Processor [410fd034] revision 4 (ARMv7), cr=10c5383d
[    0.000000] CPU: div instructions available: patching division code
[    0.000000] CPU: PIPT / VIPT nonaliasing data cache, VIPT aliasing instruction cache
[    0.000000] OF: fdt: Machine model: Raspberry Pi 3 Model B Plus Rev 1.3
[    0.000000] Memory policy: Data cache writealloc
[    0.000000] Reserved memory: created CMA memory pool at 0x37400000, size 64 MiB
[    0.000000] OF: reserved mem: initialized node linux,cma, compatible id shared-dma-pool
[    0.000000] On node 0 totalpages: 242688
[    0.000000]   Normal zone: 2133 pages used for memmap
[    0.000000]   Normal zone: 0 pages reserved
[    0.000000]   Normal zone: 242688 pages, LIFO batch:63
[    0.000000] percpu: Embedded 20 pages/cpu s49740 r8192 d23988 u81920
[    0.000000] pcpu-alloc: s49740 r8192 d23988 u81920 alloc=20*4096
[    0.000000] pcpu-alloc: [0] 0 [0] 1 [0] 2 [0] 3
[    0.000000] Built 1 zonelists, mobility grouping on.  Total pages: 240555
[    0.000000] Kernel command line: coherent_pool=1M 8250.nr_uarts=0 snd_bcm2835.enable_compat_alsa=0 snd_bcm2835.enable_hdmi=1 bcm2708_fb.fbwidth=1920 bcm2708_fb.fbheight=1080 bcm2708_fb.fbdepth=16 bcm2708_fb.fbswap=1 vc_mem.mem_base=0x3ec00000 vc_mem.mem_size=0x40000000  console=ttyS0,115200 console=tty1 root=PARTUUID=54744e88-02 rootfstype=ext4 elevator=deadline fsck.repair=yes rootwait quiet splash plymouth.ignore-serial-consoles
[    0.000000] Dentry cache hash table entries: 131072 (order: 7, 524288 bytes, linear)
[    0.000000] Inode-cache hash table entries: 65536 (order: 6, 262144 bytes, linear)
[    0.000000] mem auto-init: stack:off, heap alloc:off, heap free:off
[    0.000000] Memory: 880476K/970752K available (9216K kernel code, 698K rwdata, 2608K rodata, 1024K init, 827K bss, 24740K reserved, 65536K cma-reserved)
[    0.000000] SLUB: HWalign=64, Order=0-3, MinObjects=0, CPUs=4, Nodes=1
[    0.000000] ftrace: allocating 29205 entries in 58 pages
[    0.000000] rcu: Hierarchical RCU implementation.
[    0.000000] rcu: RCU calculated value of scheduler-enlistment delay is 10 jiffies.
[    0.000000] NR_IRQS: 16, nr_irqs: 16, preallocated irqs: 16
[    0.000000] random: get_random_bytes called from start_kernel+0x324/0x4f8 with crng_init=0
[    0.000000] arch_timer: cp15 timer(s) running at 19.20MHz (phys).
[    0.000000] clocksource: arch_sys_counter: mask: 0xffffffffffffff max_cycles: 0x46d987e47, max_idle_ns: 440795202767 ns
[    0.000006] sched_clock: 56 bits at 19MHz, resolution 52ns, wraps every 4398046511078ns
[    0.000017] Switching to timer-based delay loop, resolution 52ns
[    0.000279] Console: colour dummy device 80x30
[    0.000307] printk: console [tty1] enabled
[    0.000356] Calibrating delay loop (skipped), value calculated using timer frequency.. 38.40 BogoMIPS (lpj=192000)
[    0.000374] pid_max: default: 32768 minimum: 301
[    0.000560] LSM: Security Framework initializing
[    0.000776] Mount-cache hash table entries: 2048 (order: 1, 8192 bytes, linear)
[    0.000796] Mountpoint-cache hash table entries: 2048 (order: 1, 8192 bytes, linear)
[    0.002237] Disabling memory control group subsystem
[    0.002356] CPU: Testing write buffer coherency: ok
[    0.002917] CPU0: thread -1, cpu 0, socket 0, mpidr 80000000
[    0.003855] Setting up static identity map for 0x100000 - 0x10003c
[    0.004054] rcu: Hierarchical SRCU implementation.
[    0.004735] smp: Bringing up secondary CPUs ...
[    0.005861] CPU1: thread -1, cpu 1, socket 0, mpidr 80000001
[    0.007134] CPU2: thread -1, cpu 2, socket 0, mpidr 80000002
[    0.008296] CPU3: thread -1, cpu 3, socket 0, mpidr 80000003
[    0.008452] smp: Brought up 1 node, 4 CPUs
[    0.008468] SMP: Total of 4 processors activated (153.60 BogoMIPS).
[    0.008478] CPU: All CPU(s) started in HYP mode.
[    0.008486] CPU: Virtualization extensions available.
[    0.009452] devtmpfs: initialized
[    0.025966] VFP support v0.3: implementor 41 architecture 3 part 40 variant 3 rev 4
[    0.026237] clocksource: jiffies: mask: 0xffffffff max_cycles: 0xffffffff, max_idle_ns: 19112604462750000 ns
[    0.026264] futex hash table entries: 1024 (order: 4, 65536 bytes, linear)
[    0.029520] pinctrl core: initialized pinctrl subsystem
[    0.030687] NET: Registered protocol family 16
[    0.035025] DMA: preallocated 1024 KiB pool for atomic coherent allocations
[    0.039706] audit: initializing netlink subsys (disabled)
[    0.039981] audit: type=2000 audit(0.030:1): state=initialized audit_enabled=0 res=1
[    0.041541] hw-breakpoint: found 5 (+1 reserved) breakpoint and 4 watchpoint registers.
[    0.041552] hw-breakpoint: maximum watchpoint size is 8 bytes.
[    0.041769] Serial: AMBA PL011 UART driver
[    0.043750] bcm2835-mbox 3f00b880.mailbox: mailbox enabled
[    0.060089] raspberrypi-firmware soc:firmware: Attached to firmware from 2021-01-08 14:33, variant start
[    0.070104] raspberrypi-firmware soc:firmware: Firmware hash is 194a85abd768c7334bbadc3f1911c10a7d18ed14
[    0.120827] bcm2835-dma 3f007000.dma: DMA legacy API manager, dmachans=0x1
[    0.122990] SCSI subsystem initialized
[    0.123233] usbcore: registered new interface driver usbfs
[    0.123306] usbcore: registered new interface driver hub
[    0.123432] usbcore: registered new device driver usb
[    0.125453] clocksource: Switched to clocksource arch_sys_counter
[    1.382873] VFS: Disk quotas dquot_6.6.0
[    1.382981] VFS: Dquot-cache hash table entries: 1024 (order 0, 4096 bytes)
[    1.383215] FS-Cache: Loaded
[    1.383445] CacheFiles: Loaded
[    1.393973] thermal_sys: Registered thermal governor 'step_wise'
[    1.394358] NET: Registered protocol family 2
[    1.395222] tcp_listen_portaddr_hash hash table entries: 512 (order: 0, 6144 bytes, linear)
[    1.395265] TCP established hash table entries: 8192 (order: 3, 32768 bytes, linear)
[    1.395385] TCP bind hash table entries: 8192 (order: 4, 65536 bytes, linear)
[    1.395628] TCP: Hash tables configured (established 8192 bind 8192)
[    1.395803] UDP hash table entries: 512 (order: 2, 16384 bytes, linear)
[    1.395855] UDP-Lite hash table entries: 512 (order: 2, 16384 bytes, linear)
[    1.396147] NET: Registered protocol family 1
[    1.396972] RPC: Registered named UNIX socket transport module.
[    1.396982] RPC: Registered udp transport module.
[    1.396992] RPC: Registered tcp transport module.
[    1.397001] RPC: Registered tcp NFSv4.1 backchannel transport module.
[    1.398777] hw perfevents: enabled with armv7_cortex_a7 PMU driver, 7 counters available
[    1.402080] Initialise system trusted keyrings
[    1.402314] workingset: timestamp_bits=14 max_order=18 bucket_order=4
[    1.413786] FS-Cache: Netfs 'nfs' registered for caching
[    1.414587] NFS: Registering the id_resolver key type
[    1.414658] Key type id_resolver registered
[    1.414668] Key type id_legacy registered
[    1.414688] nfs4filelayout_init: NFSv4 File Layout Driver Registering...
[    1.416022] Key type asymmetric registered
[    1.416033] Asymmetric key parser 'x509' registered
[    1.416096] Block layer SCSI generic (bsg) driver version 0.4 loaded (major 249)
[    1.416108] io scheduler mq-deadline registered
[    1.416119] io scheduler kyber registered
[    1.419535] bcm2708_fb soc:fb: FB found 1 display(s)
[    1.441570] Console: switching to colour frame buffer device 240x67
[    1.457500] bcm2708_fb soc:fb: Registered framebuffer for display 0, size 1920x1080
[    1.462590] bcm2835-rng 3f104000.rng: hwrng registered
[    1.463059] vc-mem: phys_addr:0x00000000 mem_base=0x3ec00000 mem_size:0x40000000(1024 MiB)
[    1.463739] vc-sm: Videocore shared memory driver
[    1.464191] gpiomem-bcm2835 3f200000.gpiomem: Initialised: Registers at 0x3f200000
[    1.477218] brd: module loaded
[    1.489757] loop: module loaded
[    1.491117] Loading iSCSI transport class v2.0-870.
[    1.492001] libphy: Fixed MDIO Bus: probed
[    1.492114] usbcore: registered new interface driver lan78xx
[    1.492177] usbcore: registered new interface driver smsc95xx
[    1.492199] dwc_otg: version 3.00a 10-AUG-2012 (platform bus)
[    2.220457] Core Release: 2.80a
[    2.220470] Setting default values for core params
[    2.220498] Finished setting default values for core params
[    2.420889] Using Buffer DMA mode
[    2.420900] Periodic Transfer Interrupt Enhancement - disabled
[    2.420909] Multiprocessor Interrupt Enhancement - disabled
[    2.420921] OTG VER PARAM: 0, OTG VER FLAG: 0
[    2.420947] Dedicated Tx FIFOs mode
[    2.421649] WARN::dwc_otg_hcd_init:1074: FIQ DMA bounce buffers: virt = b7514000 dma = 0xf7514000 len=9024
[    2.421679] FIQ FSM acceleration enabled for :
               Non-periodic Split Transactions
               Periodic Split Transactions
               High-Speed Isochronous Endpoints
               Interrupt/Control Split Transaction hack enabled
[    2.421691] dwc_otg: Microframe scheduler enabled
[    2.421761] WARN::hcd_init_fiq:457: FIQ on core 1
[    2.421772] WARN::hcd_init_fiq:458: FIQ ASM at 8070bf24 length 36
[    2.421783] WARN::hcd_init_fiq:497: MPHI regs_base at bb810000
[    2.421803] dwc_otg 3f980000.usb: DWC OTG Controller
[    2.421841] dwc_otg 3f980000.usb: new USB bus registered, assigned bus number 1
[    2.421889] dwc_otg 3f980000.usb: irq 56, io mem 0x00000000
[    2.421942] Init: Port Power? op_state=1
[    2.421951] Init: Power Port (0)
[    2.422327] usb usb1: New USB device found, idVendor=1d6b, idProduct=0002, bcdDevice= 5.04
[    2.422343] usb usb1: New USB device strings: Mfr=3, Product=2, SerialNumber=1
[    2.422357] usb usb1: Product: DWC OTG Controller
[    2.422370] usb usb1: Manufacturer: Linux 5.4.83-v7+ dwc_otg_hcd
[    2.422383] usb usb1: SerialNumber: 3f980000.usb
[    2.423067] hub 1-0:1.0: USB hub found
[    2.423145] hub 1-0:1.0: 1 port detected
[    2.423905] dwc_otg: FIQ enabled
[    2.423915] dwc_otg: NAK holdoff enabled
[    2.423924] dwc_otg: FIQ split-transaction FSM enabled
[    2.423940] Module dwc_common_port init
[    2.424265] usbcore: registered new interface driver usb-storage
[    2.424461] mousedev: PS/2 mouse device common for all mice
[    2.425663] bcm2835-wdt bcm2835-wdt: Broadcom BCM2835 watchdog timer
[    2.428539] sdhci: Secure Digital Host Controller Interface driver
[    2.428549] sdhci: Copyright(c) Pierre Ossman
[    2.429142] mmc-bcm2835 3f300000.mmcnr: could not get clk, deferring probe
[    2.429790] sdhost-bcm2835 3f202000.mmc: could not get clk, deferring probe
[    2.430003] sdhci-pltfm: SDHCI platform and OF driver helper
[    2.431861] ledtrig-cpu: registered to indicate activity on CPUs
[    2.432144] hidraw: raw HID events driver (C) Jiri Kosina
[    2.432325] usbcore: registered new interface driver usbhid
[    2.432334] usbhid: USB HID core driver
[    2.433402] vchiq: vchiq_init_state: slot_zero = (ptrval)
[    2.435208] [vc_sm_connected_init]: start
[    2.444287] [vc_sm_connected_init]: end - returning 0
[    2.446285] Initializing XFRM netlink socket
[    2.446323] NET: Registered protocol family 17
[    2.446465] Key type dns_resolver registered
[    2.447234] Registering SWP/SWPB emulation handler
[    2.447570] registered taskstats version 1
[    2.447591] Loading compiled-in X.509 certificates
[    2.448120] Key type ._fscrypt registered
[    2.448130] Key type .fscrypt registered
[    2.458847] uart-pl011 3f201000.serial: cts_event_workaround enabled
[    2.458953] 3f201000.serial: ttyAMA0 at MMIO 0x3f201000 (irq = 81, base_baud = 0) is a PL011 rev2
[    2.460892] bcm2835-power bcm2835-power: Broadcom BCM2835 power domains driver
[    2.462394] mmc-bcm2835 3f300000.mmcnr: mmc_debug:0 mmc_debug2:0
[    2.462408] mmc-bcm2835 3f300000.mmcnr: DMA channel allocated
[    2.486681] sdhost: log_buf @ (ptrval) (f7513000)
[    2.527255] mmc1: queuing unknown CIS tuple 0x80 (2 bytes)
[    2.528909] mmc1: queuing unknown CIS tuple 0x80 (3 bytes)
[    2.530561] mmc1: queuing unknown CIS tuple 0x80 (3 bytes)
[    2.533524] mmc1: queuing unknown CIS tuple 0x80 (7 bytes)
[    2.536212] mmc0: sdhost-bcm2835 loaded - DMA enabled (>1)
[    2.538821] of_cfs_init
[    2.538978] of_cfs_init: OK
[    2.540108] Waiting for root device PARTUUID=54744e88-02...
[    2.600992] random: fast init done
[    2.619917] mmc1: new high speed SDIO card at address 0001
[    2.626046] mmc0: host does not support reading read-only switch, assuming write-enable
[    2.630247] mmc0: new high speed SDHC card at address aaaa
[    2.631253] mmcblk0: mmc0:aaaa SC32G 29.7 GiB
[    2.634852]  mmcblk0: p1 p2
[    2.636662] Indeed it is in host mode hprt0 = 00021501
[    2.667443] EXT4-fs (mmcblk0p2): INFO: recovery required on readonly filesystem
[    2.667456] EXT4-fs (mmcblk0p2): write access will be enabled during recovery
[    2.845503] usb 1-1: new high-speed USB device number 2 using dwc_otg
[    2.845659] Indeed it is in host mode hprt0 = 00001101
[    3.085921] usb 1-1: New USB device found, idVendor=0424, idProduct=2514, bcdDevice= b.b3
[    3.085939] usb 1-1: New USB device strings: Mfr=0, Product=0, SerialNumber=0
[    3.086691] hub 1-1:1.0: USB hub found
[    3.086810] hub 1-1:1.0: 4 ports detected
[    3.405514] usb 1-1.1: new high-speed USB device number 3 using dwc_otg
[    3.502524] EXT4-fs (mmcblk0p2): orphan cleanup on readonly fs
[    3.503739] EXT4-fs (mmcblk0p2): 9 orphan inodes deleted
[    3.503752] EXT4-fs (mmcblk0p2): recovery complete
[    3.518270] EXT4-fs (mmcblk0p2): mounted filesystem with ordered data mode. Opts: (null)
[    3.518390] VFS: Mounted root (ext4 filesystem) readonly on device 179:2.
[    3.520184] devtmpfs: mounted
[    3.526779] Freeing unused kernel memory: 1024K
[    3.535987] Run /sbin/init as init process
[    3.536226] usb 1-1.1: New USB device found, idVendor=0424, idProduct=2514, bcdDevice= b.b3
[    3.536242] usb 1-1.1: New USB device strings: Mfr=0, Product=0, SerialNumber=0
[    3.536956] hub 1-1.1:1.0: USB hub found
[    3.537071] hub 1-1.1:1.0: 3 ports detected
[    3.855536] usb 1-1.1.3: new high-speed USB device number 4 using dwc_otg
[    3.988391] usb 1-1.1.3: New USB device found, idVendor=05e3, idProduct=0610, bcdDevice= 6.54
[    3.988411] usb 1-1.1.3: New USB device strings: Mfr=1, Product=2, SerialNumber=0
[    3.988425] usb 1-1.1.3: Product: USB2.1 Hub
[    3.988438] usb 1-1.1.3: Manufacturer: GenesysLogic
[    3.989291] hub 1-1.1.3:1.0: USB hub found
[    3.989616] hub 1-1.1.3:1.0: 4 ports detected
[    4.117021] systemd[1]: System time before build time, advancing clock.
[    4.265007] NET: Registered protocol family 10
[    4.266490] Segment Routing with IPv6
[    4.296832] systemd[1]: systemd 241 running in system mode. (+PAM +AUDIT +SELINUX +IMA +APPARMOR +SMACK +SYSVINIT +UTMP +LIBCRYPTSETUP +GCRYPT +GNUTLS +ACL +XZ +LZ4 +SECCOMP +BLKID +ELFUTILS +KMOD -IDN2 +IDN -PCRE2 default-hierarchy=hybrid)
[    4.297871] systemd[1]: Detected architecture arm.
[    4.305584] usb 1-1.1.1: new high-speed USB device number 5 using dwc_otg
[    4.350628] systemd[1]: Set hostname to <raspberrypi>.
[    4.446855] usb 1-1.1.1: New USB device found, idVendor=0424, idProduct=7800, bcdDevice= 3.00
[    4.446882] usb 1-1.1.1: New USB device strings: Mfr=0, Product=0, SerialNumber=0
[    4.565600] usb 1-1.1.3.2: new full-speed USB device number 6 using dwc_otg
[    4.714646] lan78xx 1-1.1.1:1.0 (unnamed net_device) (uninitialized): No External EEPROM. Setting MAC Speed
[    4.715856] libphy: lan78xx-mdiobus: probed
[    4.736056] usb 1-1.1.3.2: New USB device found, idVendor=046d, idProduct=c52b, bcdDevice=12.11
[    4.736078] usb 1-1.1.3.2: New USB device strings: Mfr=1, Product=2, SerialNumber=0
[    4.736092] usb 1-1.1.3.2: Product: USB Receiver
[    4.736106] usb 1-1.1.3.2: Manufacturer: Logitech
[    4.744492] input: Logitech USB Receiver as /devices/platform/soc/3f980000.usb/usb1/1-1/1-1.1/1-1.1.3/1-1.1.3.2/1-1.1.3.2:1.0/0003:046D:C52B.0001/input/input0
[    4.764390] lan78xx 1-1.1.1:1.0 (unnamed net_device) (uninitialized): int urb period 64
[    4.806588] hid-generic 0003:046D:C52B.0001: input,hidraw0: USB HID v1.11 Keyboard [Logitech USB Receiver] on usb-3f980000.usb-1.1.3.2/input0
[    4.815248] input: Logitech USB Receiver Mouse as /devices/platform/soc/3f980000.usb/usb1/1-1/1-1.1/1-1.1.3/1-1.1.3.2/1-1.1.3.2:1.1/0003:046D:C52B.0002/input/input1
[    4.816132] input: Logitech USB Receiver Consumer Control as /devices/platform/soc/3f980000.usb/usb1/1-1/1-1.1/1-1.1.3/1-1.1.3.2/1-1.1.3.2:1.1/0003:046D:C52B.0002/input/input2
[    4.885985] input: Logitech USB Receiver System Control as /devices/platform/soc/3f980000.usb/usb1/1-1/1-1.1/1-1.1.3/1-1.1.3.2/1-1.1.3.2:1.1/0003:046D:C52B.0002/input/input3
[    4.886533] hid-generic 0003:046D:C52B.0002: input,hiddev96,hidraw1: USB HID v1.11 Mouse [Logitech USB Receiver] on usb-3f980000.usb-1.1.3.2/input1
[    4.893401] hid-generic 0003:046D:C52B.0003: hiddev97,hidraw2: USB HID v1.11 Device [Logitech USB Receiver] on usb-3f980000.usb-1.1.3.2/input2
[    5.015559] usb 1-1.1.3.4: new high-speed USB device number 7 using dwc_otg
[    5.185940] usb 1-1.1.3.4: New USB device found, idVendor=0409, idProduct=005a, bcdDevice= 1.00
[    5.185961] usb 1-1.1.3.4: New USB device strings: Mfr=0, Product=0, SerialNumber=0
[    5.186713] hub 1-1.1.3.4:1.0: USB hub found
[    5.186831] hub 1-1.1.3.4:1.0: 4 ports detected
[    5.338407] random: systemd: uninitialized urandom read (16 bytes read)
[    5.355886] random: systemd: uninitialized urandom read (16 bytes read)
[    5.356581] systemd[1]: Listening on Journal Audit Socket.
[    5.356991] random: systemd: uninitialized urandom read (16 bytes read)
[    5.357644] systemd[1]: Listening on Syslog Socket.
[    5.358061] systemd[1]: Listening on initctl Compatibility Named Pipe.
[    5.358874] systemd[1]: Listening on udev Control Socket.
[    5.359421] systemd[1]: Listening on udev Kernel Socket.
[    5.361569] systemd[1]: Created slice User and Session Slice.
[    5.363923] systemd[1]: Created slice system-systemd\x2dfsck.slice.
[    5.519595] usb 1-1.1.3.4.3: new high-speed USB device number 8 using dwc_otg
[    5.577910] i2c /dev entries driver
[    5.650872] usb 1-1.1.3.4.3: New USB device found, idVendor=17e9, idProduct=0156, bcdDevice= 1.33
[    5.650897] usb 1-1.1.3.4.3: New USB device strings: Mfr=1, Product=2, SerialNumber=3
[    5.650911] usb 1-1.1.3.4.3: Product: I-O DATA LCD-USB10XT
[    5.650925] usb 1-1.1.3.4.3: Manufacturer: DisplayLink
[    5.650938] usb 1-1.1.3.4.3: SerialNumber: 150▮▮▮▮▮
[    5.707225] usb-storage 1-1.1.3.4.3:2.0: USB Mass Storage device detected
[    5.745646] scsi host0: usb-storage 1-1.1.3.4.3:2.0
[    5.845585] usb 1-1.1.3.4.4: new full-speed USB device number 9 using dwc_otg
[    5.984155] usb 1-1.1.3.4.4: New USB device found, idVendor=0eef, idProduct=0001, bcdDevice= 1.00
[    5.984178] usb 1-1.1.3.4.4: New USB device strings: Mfr=1, Product=2, SerialNumber=0
[    5.984192] usb 1-1.1.3.4.4: Product: USB TouchController
[    5.984206] usb 1-1.1.3.4.4: Manufacturer: eGalax Inc.
[    5.992781] input: eGalax Inc. USB TouchController as /devices/platform/soc/3f980000.usb/usb1/1-1/1-1.1/1-1.1.3/1-1.1.3.4/1-1.1.3.4.4/1-1.1.3.4.4:1.0/0003:0EEF:0001.0004/input/input5
[    5.994518] input: eGalax Inc. USB TouchController Touchscreen as /devices/platform/soc/3f980000.usb/usb1/1-1/1-1.1/1-1.1.3/1-1.1.3.4/1-1.1.3.4.4/1-1.1.3.4.4:1.0/0003:0EEF:0001.0004/input/input6
[    5.995083] hid-generic 0003:0EEF:0001.0004: input,hidraw3: USB HID v2.10 Pointer [eGalax Inc. USB TouchController] on usb-3f980000.usb-1.1.3.4.4/input0
[    6.209748] EXT4-fs (mmcblk0p2): re-mounted. Opts: (null)
[    6.326301] systemd-journald[112]: Received request to flush runtime journal from PID 1
[    6.798305] scsi host0: scsi scan: INQUIRY result too short (5), using 36
[    6.798336] scsi 0:0:0:0: CD-ROM                                           PQ: 0 ANSI: 0
[    7.763612] usbcore: registered new interface driver uas
[    8.088469] vc_sm_cma: module is from the staging directory, the quality is unknown, you have been warned.
[    8.091195] bcm2835_vc_sm_cma_probe: Videocore shared memory driver
[    8.091220] [vc_sm_connected_init]: start
[    8.103569] [vc_sm_connected_init]: installed successfully
[    8.110070] mc: Linux media interface: v0.10
[    8.113859] snd_bcm2835: module is from the staging directory, the quality is unknown, you have been warned.
[    8.125300] bcm2835_audio bcm2835_audio: card created with 4 channels
[    8.153159] bcm2835_audio bcm2835_audio: card created with 4 channels
[    8.176122] videodev: Linux video capture interface: v2.00
[    8.265751] bcm2835_mmal_vchiq: module is from the staging directory, the quality is unknown, you have been warned.
[    8.273681] bcm2835_mmal_vchiq: module is from the staging directory, the quality is unknown, you have been warned.
[    8.282819] bcm2835_isp: module is from the staging directory, the quality is unknown, you have been warned.
[    8.282828] bcm2835_v4l2: module is from the staging directory, the quality is unknown, you have been warned.
[    8.291915] bcm2835_codec: module is from the staging directory, the quality is unknown, you have been warned.
[    8.297106] bcm2835-isp bcm2835-isp: Device node output[0] registered as /dev/video13
[    8.302410] bcm2835-isp bcm2835-isp: Device node capture[0] registered as /dev/video14
[    8.303159] bcm2835-isp bcm2835-isp: Device node capture[1] registered as /dev/video15
[    8.303557] bcm2835-isp bcm2835-isp: Device node stats[2] registered as /dev/video16
[    8.303589] bcm2835-isp bcm2835-isp: Register output node 0 with media controller
[    8.303610] bcm2835-isp bcm2835-isp: Register capture node 1 with media controller
[    8.303649] bcm2835-isp bcm2835-isp: Register capture node 2 with media controller
[    8.303668] bcm2835-isp bcm2835-isp: Register capture node 3 with media controller
[    8.303904] bcm2835-isp bcm2835-isp: Loaded V4L2 bcm2835-isp
[    8.317240] bcm2835-codec bcm2835-codec: Device registered as /dev/video10
[    8.317292] bcm2835-codec bcm2835-codec: Loaded V4L2 decode
[    8.334923] bcm2835-codec bcm2835-codec: Device registered as /dev/video11
[    8.334989] bcm2835-codec bcm2835-codec: Loaded V4L2 encode
[    8.421724] bcm2835-codec bcm2835-codec: Device registered as /dev/video12
[    8.421777] bcm2835-codec bcm2835-codec: Loaded V4L2 isp
[    8.843377] cfg80211: Loading compiled-in X.509 certificates for regulatory database
[    8.994309] cfg80211: Loaded X.509 cert 'sforshee: 00b28ddf47aef9cea7'
[    9.108130] brcmfmac: F1 signature read @0x18000000=0x15264345
[    9.131428] brcmfmac: brcmf_fw_alloc_request: using brcm/brcmfmac43455-sdio for chip BCM4345/6
[    9.133683] usbcore: registered new interface driver brcmfmac
[    9.187314] brcmfmac mmc1:0001:1: Direct firmware load for brcm/brcmfmac43455-sdio.raspberrypi,3-model-b-plus.txt failed with error -2
[    9.406830] random: crng init done
[    9.406846] random: 7 urandom warning(s) missed due to ratelimiting
[    9.444078] usbcore: registered new interface driver usbtouchscreen
[    9.446986] brcmfmac: brcmf_fw_alloc_request: using brcm/brcmfmac43455-sdio for chip BCM4345/6
[    9.526469] brcmfmac: brcmf_c_preinit_dcmds: Firmware: BCM4345/6 wl0: Mar 23 2020 02:19:54 version 7.45.206 (r725000 CY) FWID 01-88ee44ea
[    9.673649] logitech-djreceiver 0003:046D:C52B.0003: hiddev96,hidraw0: USB HID v1.11 Device [Logitech USB Receiver] on usb-3f980000.usb-1.1.3.2/input2
[    9.811946] input: Logitech Unifying Device. Wireless PID:4003 Keyboard as /devices/platform/soc/3f980000.usb/usb1/1-1/1-1.1/1-1.1.3/1-1.1.3.2/1-1.1.3.2:1.2/0003:046D:C52B.0003/0003:046D:4003.0005/input/input7
[    9.813501] input: Logitech Unifying Device. Wireless PID:4003 Consumer Control as /devices/platform/soc/3f980000.usb/usb1/1-1/1-1.1/1-1.1.3/1-1.1.3.2/1-1.1.3.2:1.2/0003:046D:C52B.0003/0003:046D:4003.0005/input/input8
[    9.813933] input: Logitech Unifying Device. Wireless PID:4003 System Control as /devices/platform/soc/3f980000.usb/usb1/1-1/1-1.1/1-1.1.3/1-1.1.3.2/1-1.1.3.2:1.2/0003:046D:C52B.0003/0003:046D:4003.0005/input/input9
[    9.814457] hid-generic 0003:046D:4003.0005: input,hidraw1: USB HID v1.11 Keyboard [Logitech Unifying Device. Wireless PID:4003] on usb-3f980000.usb-1.1.3.2/input2:2
[    9.957243] scsi 0:0:0:0: Attached scsi generic sg0 type 5
[    9.978404] sr 0:0:0:0: [sr0] scsi3-mmc drive: 8x/40x writer xa/form2 cdda tray
[    9.978424] cdrom: Uniform CD-ROM driver Revision: 3.20
[   10.086463] sr 0:0:0:0: Attached scsi CD-ROM sr0
[   10.712024] dwc_otg 3f980000.usb: dev 1.1.3.4.3 ep4in scatterlist error -121/-121
[   11.137176] input: Logitech K270 as /devices/platform/soc/3f980000.usb/usb1/1-1/1-1.1/1-1.1.3/1-1.1.3.2/1-1.1.3.2:1.2/0003:046D:C52B.0003/0003:046D:4003.0005/input/input13
[   11.144316] logitech-hidpp-device 0003:046D:4003.0005: input,hidraw1: USB HID v1.11 Keyboard [Logitech K270] on usb-3f980000.usb-1.1.3.2/input2:2
[   11.848647] uart-pl011 3f201000.serial: no DMA platform data
[   11.971646] 8021q: 802.1Q VLAN Support v1.8
[   12.495706] Adding 102396k swap on /var/swap.  Priority:-2 extents:1 across:102396k SSFS
[   12.886108] brcmfmac: brcmf_cfg80211_set_power_mgmt: power save enabled
[   13.491548] 8021q: adding VLAN 0 to HW filter on device eth0
[   18.557439] IPv6: ADDRCONF(NETDEV_CHANGE): wlan0: link becomes ready
[   18.636246] Bluetooth: Core ver 2.22
[   18.636310] NET: Registered protocol family 31
[   18.636315] Bluetooth: HCI device and connection manager initialized
[   18.636334] Bluetooth: HCI socket layer initialized
[   18.636343] Bluetooth: L2CAP socket layer initialized
[   18.636358] Bluetooth: SCO socket layer initialized
[   18.646948] Bluetooth: HCI UART driver ver 2.3
[   18.646962] Bluetooth: HCI UART protocol H4 registered
[   18.647007] Bluetooth: HCI UART protocol Three-wire (H5) registered
[   18.647165] Bluetooth: HCI UART protocol Broadcom registered
[   18.874265] Bluetooth: BNEP (Ethernet Emulation) ver 1.3
[   18.874277] Bluetooth: BNEP filters: protocol multicast
[   18.874297] Bluetooth: BNEP socket layer initialized
[   19.929792] ICMPv6: process `dhcpcd' is using deprecated sysctl (syscall) net.ipv6.neigh.wlan0.retrans_time - use net.ipv6.neigh.wlan0.retrans_time_ms instead
[   20.959638] fuse: init (API version 7.31)
[   22.778207] Bluetooth: RFCOMM TTY layer initialized
[   22.778247] Bluetooth: RFCOMM socket layer initialized
[   22.778278] Bluetooth: RFCOMM ver 1.11
[   31.195688] Under-voltage detected! (0x00050005)
[   37.435608] Voltage normalised (0x00000000)
[   48.555550] usb 1-1.1.3.3: new full-speed USB device number 10 using dwc_otg
[   48.714167] usb 1-1.1.3.3: New USB device found, idVendor=1ea7, idProduct=0066, bcdDevice= 2.00
[   48.714186] usb 1-1.1.3.3: New USB device strings: Mfr=0, Product=1, SerialNumber=0
[   48.714198] usb 1-1.1.3.3: Product: 2.4G Mouse
[   48.725654] input: 2.4G Mouse as /devices/platform/soc/3f980000.usb/usb1/1-1/1-1.1/1-1.1.3/1-1.1.3.3/1-1.1.3.3:1.0/0003:1EA7:0066.0006/input/input14
[   48.796873] hid-generic 0003:1EA7:0066.0006: input,hidraw2: USB HID v1.10 Keyboard [2.4G Mouse] on usb-3f980000.usb-1.1.3.3/input0
[   48.806093] input: 2.4G Mouse as /devices/platform/soc/3f980000.usb/usb1/1-1/1-1.1/1-1.1.3/1-1.1.3.3/1-1.1.3.3:1.1/0003:1EA7:0066.0007/input/input15
[   48.806523] input: 2.4G Mouse as /devices/platform/soc/3f980000.usb/usb1/1-1/1-1.1/1-1.1.3/1-1.1.3.3/1-1.1.3.3:1.1/0003:1EA7:0066.0007/input/input16
[   48.807088] input: 2.4G Mouse Consumer Control as /devices/platform/soc/3f980000.usb/usb1/1-1/1-1.1/1-1.1.3/1-1.1.3.3/1-1.1.3.3:1.1/0003:1EA7:0066.0007/input/input17
[   48.876189] input: 2.4G Mouse System Control as /devices/platform/soc/3f980000.usb/usb1/1-1/1-1.1/1-1.1.3/1-1.1.3.3/1-1.1.3.3:1.1/0003:1EA7:0066.0007/input/input18
[   48.876778] hid-generic 0003:1EA7:0066.0007: input,hiddev97,hidraw4: USB HID v1.10 Mouse [2.4G Mouse] on usb-3f980000.usb-1.1.3.3/input1
[   62.078504] logitech-hidpp-device 0003:046D:4003.0005: HID++ 2.0 device connected.

特にエラーはログされていませんが、LCD-USBに出力が表示された時のカーネルメッセージにはログされている、次の様な:

[ 14.105704] udlfb 1-1.1.3.4.3:1.0: vendor descriptor length: 23 data: 17 5f 01 00 15 05 00 01 03 00 04
[ 14.105727] udlfb 1-1.1.3.4.3:1.0: DL chip limited to 700000 pixel modes
[ 14.155580] usb 1-1.1.3.4.3: fb1 is DisplayLink USB device (1024x600, 2400K framebuffer memory)
[ 14.155808] usbcore: registered new interface driver udlfb
[ 14.355111] usbcore: registered new interface driver udl

といったudlfs/udlドライバー登録を確認出来るログは含まれていないので、ログを見る限りではXorgサーバーを起動する以前の起動時に何かの不都合が起きていると思われます。

加えて、少し気になるのは、表示がされる/されない時のログの両方で、EXT-4-fsでフォーマットされているrootをシステムにマウントする時点でファイルシステムのリカバリー (recovery) が行われています。

[    2.667443] EXT4-fs (mmcblk0p2): INFO: recovery required on readonly filesystem
[    2.667456] EXT4-fs (mmcblk0p2): write access will be enabled during recovery

:::

[    3.502524] EXT4-fs (mmcblk0p2): orphan cleanup on readonly fs
[    3.503739] EXT4-fs (mmcblk0p2): 9 orphan inodes deleted
[    3.503752] EXT4-fs (mmcblk0p2): recovery complete
[    3.518270] EXT4-fs (mmcblk0p2): mounted filesystem with ordered data mode. Opts: (null)
[    3.518390] VFS: Mounted root (ext4 filesystem) readonly on device 179:2.

:::

[    6.209748] EXT4-fs (mmcblk0p2): re-mounted. Opts: (null)

Linuxだと前回の起動時にrootをアンマウントする前に電源が落ちてしまうと良くある事例で、突然電源が落ちて再起動をした場合や、シャットダウンが完全に終る前に電源を切ってしまった場合でも良く見られます。

起動時のリカバリーが原因でudlfbドライバーが登録されないのかどうかは何とも言えませんが、リカバリーにかかる時間は影響が出ているデータ領域の種類や大きさにもよるので、システム起動時のUSB機器の初期化のタイミングに影響する可能性もあります。

WindowsやMacといった自動的に電源が切れるタイプのOSを使い慣れている人にはあまり縁のない事かもしれませんが、ラズビアンの様に、組み込み式のLinuxだと電源を手動で操作する必要があって、タイミングを間違えるとファイルが破損してしまう場合もあります。

ラズベリーパイの場合はボード上の緑のLEDが点灯しなくなるまで待たないといけないのですが、以前にラズベリーパイの電源に関する記事で説明をしているので詳しくはその記事を参照してみて下さい 👉『📃ラズベリーパイ: シャットダウンボタンを1行で有効化』

因みにgitlineさんの2021年3月14日 23:18付けのコメントに:

モニタは電圧不足を補うために、セルフパワーのUSBハブ経由で接続しています(それでもlow voltageとなることがちょくちょくありますが…)

とありますが、LCD-USB7XW/Bはバスパワーの機器ですが、使われているLCD-USB10XB-Tの方はバスパワーでなくACアダプター駆動になるのでUSBポートからの電力(5V 上限500mA)で十分動作しそうな気がしますが (そうでない可能性もあるかもしれませんが)。。

LCD-USB10XB-Tをラズベリーパイと使っている場合で、もしも、『Low Voltage』のメッセージが頻繁にログや画面上に表示される場合は、ラズベリーパイ本体の電源用のACアダプターとケーブルの電流の上限が、使っているラズベリーパイの推奨電流容量と以上である事も確認してみる良いと思います。

ラズベリーパイ本家の📃電源についてのページ (英文)によるとラズベリーパイ 3B+ の場合は 2.5Aが推奨になっているのでアダプターとケーブル共に2.5A以上に対応の物を使う事をお勧めします。

アダプターに関しては本体に表示があると思うでの比較的簡単に電流容量を確認出来ると思いますが、ケーブルに関しては、ケーブル内の銅線の太さで電流の容量が変わってきますが、この情報がケーブルに表示されている可能性は低いので、電流容量が明記されている商品を購入するのが確実かと思います。

udlfsドライバーについてはカーネルログを見た限りでは解決策になる様なヒントは見つけられませんでしたが、現時点では

• 『Low Voltage』の問題と
• 起動時のrootリカバリーに関連する問題

を解消した状態でLCD-USBを安定起動出来るかどうかを確認してみると良いかもしれません。

もう一つは仮にモニタ出力されたとしても、拡張モードにならないこと。
また、HDMIと同じ画面サイズで出力されているのかわかりませんが、かなりの範囲が見切れています。写真は取ったのですが画像は貼れないみたいです…

こちらはXorgの設定になると思うのですが、もう少し時間を掛けてXorg.0.logを見て、後日追記したいと思います。

関連記事

ラズベリーパイとLCD-USB7XW/BとLCD-USB10XB-T (前編)
ラズベリーパイとLCD-USB7XW/BとLCD-USB10XB-T (後編: Part1)
ラズベリーパイとLCD-USB7XW/BとLCD-USB10XB-T (後編: Part2)