Ever since I installed Ubuntu 18.04 on my EliteBook 820 g1 (refurbished), I'm experiencing a very annoying problem. Ever so often, the display randomly shuts down, while the backlight stays on. The rest of the computer works just fine, but the display is gone. Going in suspension and then restarting the system usually fixes matters, but it's still really annoying.
I've been experiencing this issue since installing the new LTS (never with 16.04), and I've searched the web far and wide, in the vain hope of finding something relevant. Two clean reinstalls of the system have born no change.
For reference, this is the output of dmesg right after a display-shutdown/suspend/resume:
[12393.620657] Disabling non-boot CPUs ... [12393.634014] IRQ 51: no longer affine to CPU1 [12393.635065] smpboot: CPU 1 is now offline [12393.658070] IRQ 49: no longer affine to CPU2 [12393.659106] smpboot: CPU 2 is now offline [12393.677989] IRQ 17: no longer affine to CPU3 [12393.678003] IRQ 44: no longer affine to CPU3 [12393.678009] IRQ 45: no longer affine to CPU3 [12393.679030] smpboot: CPU 3 is now offline [12393.682419] ACPI: Low-level resume complete [12393.682533] ACPI: EC: EC started [12393.682534] PM: Restoring platform NVS memory [12393.689121] Enabling non-boot CPUs ... [12393.689264] x86: Booting SMP configuration: [12393.689267] smpboot: Booting Node 0 Processor 1 APIC 0x1 [12393.690569] cache: parent cpu1 should not be sleeping [12393.690998] CPU1 is up [12393.691071] smpboot: Booting Node 0 Processor 2 APIC 0x2 [12393.696405] cache: parent cpu2 should not be sleeping [12393.696884] CPU2 is up [12393.696932] smpboot: Booting Node 0 Processor 3 APIC 0x3 [12393.697934] cache: parent cpu3 should not be sleeping [12393.698379] CPU3 is up [12393.706097] ACPI: Waking up from system sleep state S3 [12393.848233] ACPI: EC: interrupt unblocked [12393.983516] ACPI: EC: event unblocked [12393.989148] sd 0:0:0:0: [sda] Starting disk [12394.281026] usb 2-7: reset high-speed USB device number 5 using xhci_hcd [12394.557044] usb 2-5: reset full-speed USB device number 4 using xhci_hcd [12394.833051] usb 2-4: reset full-speed USB device number 3 using xhci_hcd [12395.545279] ACPI: button: The lid device is not compliant to SW_LID. [12395.593863] tpm tpm0: A TPM error (7) occurred attempting to read a pcr value [12395.593867] tpm tpm0: TPM is disabled/deactivated (0x7) [12395.602043] acpi LNXPOWER:02: Turning OFF [12395.602125] acpi LNXPOWER:01: Turning OFF [12395.602172] OOM killer enabled. [12395.602173] Restarting tasks ... [12395.602586] acpi PNP0501:00: Still not present [12395.614910] Bluetooth: hci0: read Intel version: 370710018002030d00 [12395.614917] Bluetooth: hci0: Intel Bluetooth firmware file: intel/ibt-hw-37.7.10-fw-188.8.131.52.d.bseq [12395.618733] acpi PNP0501:00: Still not present [12395.623484] done. [12395.685019] ata1: SATA link up 3.0 Gbps (SStatus 123 SControl 300) [12395.687424] ata1.00: configured for UDMA/133 [12395.750905] Bluetooth: hci0: Intel firmware patch completed and activated [12396.935662] PM: suspend exit [12397.093899] e1000e: enp0s25 NIC Link is Down [12397.094630] IPv6: ADDRCONF(NETDEV_UP): enp0s25: link is not ready [12397.145692] psmouse serio3: synaptics: queried max coordinates: x [..5708], y [..4660] [12397.180135] psmouse serio3: synaptics: queried min coordinates: x [1392..], y [1108..] [12397.281151] IPv6: ADDRCONF(NETDEV_UP): enp0s25: link is not ready [12397.283116] IPv6: ADDRCONF(NETDEV_UP): wlo1: link is not ready [12397.526363] IPv6: ADDRCONF(NETDEV_UP): wlo1: link is not ready [12397.585154] IPv6: ADDRCONF(NETDEV_UP): wlo1: link is not ready [12400.743556] wlo1: authenticate with a6:91:b1:b3:96:7d [12400.748826] wlo1: send auth to a6:91:b1:b3:96:7d (try 1/3) [12400.750535] wlo1: authenticated [12400.752856] wlo1: associate with a6:91:b1:b3:96:7d (try 1/3) [12400.753935] wlo1: RX AssocResp from a6:91:b1:b3:96:7d (capab=0x1011 status=0 aid=1) [12400.755378] wlo1: associated [12400.769694] IPv6: ADDRCONF(NETDEV_CHANGE): wlo1: link becomes ready [12400.847191] wlo1: Limiting TX power to 23 (23 - 0) dBm as advertised by a6:91:b1:b3:96:7d
This line in particular is highlighted in red:
[12395.593863] tpm tpm0: A TPM error (7) occurred attempting to read a pcr value
so I tried to figure out what to do with this TMP thingie, but there's no BIOS update to install, like The Internet suggested, and the TMP item in the BIOS is present but greyed out.
Still trying to figure out what's happening, but I believe it's high time I remit to the deeper expertise of this forum.