Lenovo T480s, docking station: external monitors turn black randomly

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nogo
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Lenovo T480s, docking station: external monitors turn black randomly

Post by nogo »

Hi,
my Lenovo T480s (Intel UHD Graphics 620, Linux Mint 20.3 Cinnamon, kernel 5.15.0-58) features an extremely annoying bug when connecting external monitors to its attached docking station (UltraDock, 40AJ0135EU): both of the connected screens, one at a time, suddenly turn completely black for about 2-3 seconds at apparently random times. Subsequently the screen displays a normal image. Typically just one of the two screens turns black, the other one displays a correct image. The interval of occurrence is apparently random - sometimes repeatedly black any few tens of seconds, sometimes working for more than an hour.

The problem started (imho) following a BIOS update of the T480s using fwupdmgr (to 1.52, perhaps by two versions at a time) and/or kernel updates end of November or during December 2022. Until then I had two monitors (both Dell, one 32.5" WQHD 2560x1440, one 24" WUXGA 1920x1200) attached to the dock using DP, the laptop lid was closed almost all of the time. In order to be able to work I switched to the laptop screen and one WQHD monitor only.

Some relevant facts:
- The temporary black screen (flicker) happens exclusively on external displays connected through the docking station. In particular I never saw this issue on the laptop's built-in screen.
- I tried connecting the two external screens using distinct cables and technologies (DP+DP, DP+HDMI) to the dock - still same behavior
- Recently I connected the WQHD screen using HDMI directly to the T480s built-in HDMI output (without docking station) - so far NO black flickers.
- I tried all sorts of solutions found in various forums: i915 kernel parameters, xrandr settings (bpc), etc., etc. - none of them fixed the issue
- Switching back to older kernels (5.4) did not help, on the contrary.
-

Subjectively the following modifications improved (but did not fix) the issue - i.e. reduced the frequency of blackouts:
- Connecting/using just 1 external screen instead of 2
- Reducing the resolution of the screen (i.e., WUXGA instead of WQHD).
- The xrandr modification of bcp to 8 somehow seems to reduce the frequency of the black screen occurrences - but they still happen.

The only solution that seems to work so far (haven't had a black screen for about three hours since I changed the config) is to use the laptop's HDMI socket for connecting the external screen.

Surprisingly none of the system logs (kernel, Xorg, ...) indicate any potential reasons or consequences of the black screens - there's no entry.

One open bug report matches my system's behavior quite closely: https://bugs.launchpad.net/ubuntu/+sour ... ug/1975872
Does anyone else have a similar setup and similar issues? Any suggestions on alternative solutions?

thanks in advance!
Last edited by LockBot on Tue Jul 25, 2023 10:00 pm, edited 1 time in total.
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SMG
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Re: Lenovo T480s, docking station: external monitors turn black randomly

Post by SMG »

nogo wrote: Wed Jan 25, 2023 11:03 ammy Lenovo T480s (Intel UHD Graphics 620, Linux Mint 20.3 Cinnamon, kernel 5.15.0-58)
Welcome to the forum, nogo.

Please give us information about your install by entering this command in a terminal:

Code: Select all

inxi -Fxxxrz
Click </> from the mini toolbar above the textbox where you type your reply and then place your cursor between the code tags and paste the results of the command between the code tags [code]Results[/code]. This will let us know how Mint sees your hardware.

The issue seems to be with the Ultradock and how it is seen by the laptop. Do you know if the firmware for the docking station has ever been updated? While the updates appear to be Windows only, the readme doesn't seem to mention Dell monitor fixes, but I don't know if that is something Lenovo would fix anyway.
nogo wrote: Wed Jan 25, 2023 11:03 amThe problem started (imho) following a BIOS update of the T480s using fwupdmgr (to 1.52, perhaps by two versions at a time)
It appears Version 1.53 became available yesterday and the changes are:
UEFI: 1.53 / ECP: 1.23
- [Important updates] Enhancement to address security vulnerability, CVE-2017-5715, CVE-2022-33894,
CVE-2022-34301, CVE-2022-34302, CVE-2022-34303.
- (New) Updated the Diagnostics module to version 04.28.000.
- (Fix) Fixed an issue where some monitor might not connected properly.
That last line might relate to what you have noticed?
nogo wrote: Wed Jan 25, 2023 11:03 amOne open bug report matches my system's behavior quite closely: https://bugs.launchpad.net/ubuntu/+sour ... ug/1975872
That bug is for kernel 5.15.0-33 from May of last year. That doesn't sound like your issue, especially since that person's monitor is directly connected to the laptop and not through a docking station.
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Re: Lenovo T480s, docking station: external monitors turn black randomly

Post by nogo »

SMG wrote: Fri Jan 27, 2023 9:42 pm
nogo wrote: Wed Jan 25, 2023 11:03 ammy Lenovo T480s (Intel UHD Graphics 620, Linux Mint 20.3 Cinnamon, kernel 5.15.0-58)
Welcome to the forum, nogo.
Thank you, SMG.
SMG wrote: Fri Jan 27, 2023 9:42 pm Please give us information about your install by entering this command in a terminal:

Code: Select all

inxi -Fxxxrz
Click </> from the mini toolbar above the textbox where you type your reply and then place your cursor between the code tags and paste the results of the command between the code tags [code]Results[/code]. This will let us know how Mint sees your hardware.
Nothing spectacular and suspicious, I suppose:

Code: Select all

 $ inxi -Fxxxrz
System:    Kernel: 5.15.0-58-generic x86_64 bits: 64 compiler: N/A Desktop: Cinnamon 5.2.7 wm: muffin 5.2.1 dm: LightDM 1.30.0 
           Distro: Linux Mint 20.3 Una base: Ubuntu 20.04 focal 
Machine:   Type: Laptop System: LENOVO product: 20L8S02R00 v: ThinkPad T480s serial: <filter> Chassis: type: 10 
           serial: <filter> 
           Mobo: LENOVO model: 20L8S02R00 serial: <filter> UEFI: LENOVO v: N22ET75W (1.52 ) date: 09/28/2022 
Battery:   ID-1: BAT0 charge: 53.2 Wh condition: 53.8/57.0 Wh (94%) volts: 12.4/11.5 model: SMP 01AV479 type: Li-poly 
           serial: <filter> status: Not charging cycles: 5 
CPU:       Topology: Quad Core model: Intel Core i5-8350U bits: 64 type: MT MCP arch: Kaby Lake rev: A L2 cache: 6144 KiB 
           flags: avx avx2 lm nx pae sse sse2 sse3 sse4_1 sse4_2 ssse3 vmx bogomips: 30399 
           Speed: 1200 MHz min/max: 400/3600 MHz Core speeds (MHz): 1: 1193 2: 1200 3: 1200 4: 1164 5: 801 6: 800 7: 800 
           8: 800 
Graphics:  Device-1: Intel UHD Graphics 620 vendor: Lenovo driver: i915 v: kernel bus ID: 00:02.0 chip ID: 8086:5917 
           Display: x11 server: X.Org 1.20.13 driver: modesetting unloaded: fbdev,vesa 
           resolution: 2560x1440~60Hz, 2560x1440~60Hz 
           OpenGL: renderer: Mesa Intel UHD Graphics 620 (KBL GT2) v: 4.6 Mesa 21.2.6 direct render: Yes 
Audio:     Device-1: Intel Sunrise Point-LP HD Audio vendor: Lenovo driver: snd_hda_intel v: kernel bus ID: 00:1f.3 
           chip ID: 8086:9d71 
           Device-2: Lenovo type: USB driver: hid-generic,snd-usb-audio,usbhid bus ID: 3-1.2.4:7 chip ID: 17ef:306f 
           Device-3: ARC Camera type: USB driver: snd-usb-audio,uvcvideo bus ID: 3-1.3:8 chip ID: 05a3:9331 serial: <filter> 
           Device-4: Logitech Logi USB Headset type: USB driver: hid-generic,snd-usb-audio,usbhid bus ID: 1-1:2 
           chip ID: 046d:0a8f 
           Sound Server: ALSA v: k5.15.0-58-generic 
Network:   Device-1: Intel Ethernet I219-LM vendor: Lenovo driver: e1000e v: kernel port: efa0 bus ID: 00:1f.6 
           chip ID: 8086:15d7 
           IF: enp0s31f6 state: up speed: 1000 Mbps duplex: full mac: <filter> 
           Device-2: Intel Wireless 8265 / 8275 driver: iwlwifi v: kernel port: efa0 bus ID: 3d:00.0 chip ID: 8086:24fd 
           IF: wlp61s0 state: down mac: <filter> 
Drives:    Local Storage: total: 931.51 GiB used: 763.95 GiB (82.0%) 
           ID-1: /dev/nvme0n1 vendor: Western Digital model: WDS100T3X0C-00SJG0 size: 931.51 GiB speed: 31.6 Gb/s lanes: 4 
           serial: <filter> rev: 102000WD scheme: GPT 
Partition: ID-1: / size: 913.68 GiB used: 762.54 GiB (83.5%) fs: ext4 dev: /dev/dm-1 
           ID-2: /boot size: 703.1 MiB used: 516.8 MiB (73.5%) fs: ext4 dev: /dev/nvme0n1p2 
           ID-3: swap-1 size: 976.0 MiB used: 908.3 MiB (93.1%) fs: swap dev: /dev/dm-2 
Sensors:   System Temperatures: cpu: 51.0 C mobo: N/A 
           Fan Speeds (RPM): fan-1: 0 
SMG wrote: Fri Jan 27, 2023 9:42 pm The issue seems to be with the Ultradock and how it is seen by the laptop. Do you know if the firmware for the docking station has ever been updated? While the updates appear to be Windows only, the readme doesn't seem to mention Dell monitor fixes, but I don't know if that is something Lenovo would fix anyway.
Thank you for the hint - this is exactly the track I'm on. I do know that the dock firmware has not been updated so far as I noticed on Friday that fwupdmgr does not update the FW. I hoped to find a native Windows laptop but no success so far. So the plan is to get hold of a fast USB stick, build a Win-to-go image and try to update the dock firmware first running Windows.
SMG wrote: Fri Jan 27, 2023 9:42 pm
UEFI: 1.53 / ECP: 1.23
- [Important updates] Enhancement to address security vulnerability, CVE-2017-5715, CVE-2022-33894,
CVE-2022-34301, CVE-2022-34302, CVE-2022-34303.
- (New) Updated the Diagnostics module to version 04.28.000.
- (Fix) Fixed an issue where some monitor might not connected properly.
That last line might relate to what you have noticed?
That's great news (and yes, sounds like it could fix the issue). Unfortunately 1.53 did not yet propagate to LVFS - so the plan is to do the update via Win-to-go.
Many thanks for now - will try the two updates within the next days and come back with results.
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Re: Lenovo T480s, docking station: external monitors turn black randomly

Post by SMG »

nogo wrote: Mon Jan 30, 2023 11:55 amNothing spectacular and suspicious, I suppose:
Actually, your computer's root partition is full enough it is possibly affecting graphics. The recommendation is to be below 75% full and lower is better.

Partition: ID-1: / size: 913.68 GiB used: 762.54 GiB (83.5%) fs: ext4 dev: /dev/dm-1
ID-2: /boot size: 703.1 MiB used: 516.8 MiB (73.5%) fs: ext4 dev: /dev/nvme0n1p2
ID-3: swap-1 size: 976.0 MiB used: 908.3 MiB (93.1%) fs: swap dev: /dev/dm-2

Perhaps you have old kernels you can remove. We recommend keeping the current kernel and one or two older kernels. You probably have enough 5.15 kernels that you can remove all 5.4 kernels (if you have any installed). Kernels and Timeshift snapshots are often the biggest culprits when a root partition is getting full, although someone recently had a VM they used infrequently which was taking up a huge amount of space.
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Re: Lenovo T480s, docking station: external monitors turn black randomly

Post by nogo »

SMG wrote: Mon Jan 30, 2023 1:42 pm Actually, your computer's root partition is full enough it is possibly affecting graphics. The recommendation is to be below 75% full and lower is better.

Partition: ID-1: / size: 913.68 GiB used: 762.54 GiB (83.5%) fs: ext4 dev: /dev/dm-1
ID-2: /boot size: 703.1 MiB used: 516.8 MiB (73.5%) fs: ext4 dev: /dev/nvme0n1p2
ID-3: swap-1 size: 976.0 MiB used: 908.3 MiB (93.1%) fs: swap dev: /dev/dm-2
An SSD with 140GB of free disk space affecting graphics performance is imho out of question (side-note: I use Linux on my desktop since 1995 when I installed Slackware from about 50 3.5" floppy discs. Times (and disk requirements) have changed since then - but even in the case of fragmentation etc 140GB should be more than sufficient for a complete Linux Mint installation). The boot partition (root is encrypted using luks) stores some additional kernels that I re-installed when trying to eliminate potential reasons for the graphics issue. So it's not the reason but the consequence of the graphics problem (currently I have the two latest 5.15 kernels plus the .50 version and the latest 5.4 as fallback). No timeshift (I backup externally using rsync) but you guessed right, there are some truly large VMs on root that can't be deleted. Perhaps I can eliminate some snapshots. But as I said - there were times when the disk was above 95% use and no issues.

As a status update: meanwhile I've flashed the BIOS to 1.53 and updated the docking station firmware to the latest release using a Win-to-Go disk. The black screen now happens less often. When decreasing the bpc for both monitors to 6 (xrandr --output DP-2-2 --set "max bpc" 6) I even can work for extended periods without experiencing the black screen event. But the bug is still here, even though only sporadically.

Unfortunately I've some deadlines ahead and need to focus on my work. But I hope to get some time by the mid of February to continue isolating and/or reproducing the bug. For now thank you, SMG, for your support.
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Re: Lenovo T480s, docking station: external monitors turn black randomly

Post by SMG »

nogo wrote: Tue Jan 31, 2023 4:22 amAn SSD with 140GB of free disk space affecting graphics performance is imho out of question (side-note: I use Linux on my desktop since 1995 when I installed Slackware from about 50 3.5" floppy discs. Times (and disk requirements) have changed since then - but even in the case of fragmentation etc 140GB should be more than sufficient for a complete Linux Mint installation).
My comment was not related to "fragmentation". It was related to how an SSD works and how the operating system works with regards to temporary files.
nogo wrote: Tue Jan 31, 2023 4:22 amAs a status update: meanwhile I've flashed the BIOS to 1.53 and updated the docking station firmware to the latest release using a Win-to-Go disk. The black screen now happens less often. When decreasing the bpc for both monitors to 6 (xrandr --output DP-2-2 --set "max bpc" 6) I even can work for extended periods without experiencing the black screen event.
Glad to hear you were able to make progress in reducing the problem.
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Re: Lenovo T480s, docking station: external monitors turn black randomly

Post by ivar »

We have been using Lenovo laptops + docks at work since 2016. Around 20 T480s. Some users have been plagued by this , while most have been unaffected.
When it happens, I run the lenovo system update utility + eventual thunderbolt dock software.

Sometimes, to get monitors working again, I just have to pull all display cables from the dock, then putting them back in one by one. It is really annoying to have such a persistent problem over several models / docks / monitor types without finding a "once and for all" fix.

I suspect it is related to the way the dock wakes (or not!) the monitors from power saving sleep mode
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Re: Lenovo T480s, docking station: external monitors turn black randomly

Post by greengnome »

I have a similar setup and have seen similar issues but with all hardware different (Dell Thunderbolt dock, tuxedo laptop) except the i915 graphics.
I was just starting to dig into the details when it stopped with the recent update to Mesa 22.3.7. Have you tried that and did it do anything for you?
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Re: Lenovo T480s, docking station: external monitors turn black randomly

Post by greengnome »

Never mind, it still happens for me. It just took a long time (over a week) until it triggered again.
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