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Old 09-23-2018, 03:02 PM   #16
hgcoin
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Join Date: Sep 2018
Posts: 4
Default Confirming EDID lockup after idle period 4.15.0-34-generic/ 18.04 LTS bionic

In a multimonitor setup where the displaylink 5500 usb is attached, after an idle period of some hours, the log fills with tens of thousands of
evdi: [E] evdi_painter_connect:529 Edid length too small

All screens appear dark but active (blanked, not 'sleep' or 'off'). The only remedy is to reboot - but it is possible to get a console window to do a soft-reboot. The processor is:

Intel(R) Core(TM) i7-6700 CPU @ 3.40GHz. The system is a Dell XPS 8910 MB 1.1.7 latest bios. The native HD graphics 530 v6 controls two monitors. An GM107 / Nvidia geforce gtx 750 Ti rev a2 controls three monitors. The Diamond displaylink controls one. The nvidia uses the nouveau driver.

The only other abnormal symptom is:

During normal operations, from time to time when using the USB mouse I see vertically elongated rectangle damage, perhaps 30 pixels wide and 150 tall, usually white, with a normal gap of maybe 80 pixels atop another rectangle, repeated perhaps 4 or 5 times in a vertical stripe of sorts. As the mouse moves that description of vertical screen damage gets repainted perhaps every 300 horizontal pixels as the mouse moves on the intel-chip controlled monitors. Not on the display link monitor when it works, nor the nvidia controller monitors. The screen buffer damage can be repaired by dragging any window across the damaged area.

So, I'm guessing the evdi driver in response to usb activity decides to write on the memory space used by the intel graphics chip.

Back to the displaylink evdi complaint:

Here's a fairly typical example of the onset of the problem. The system was unattended for some hours at that point:

...
Sep 21 19:03:11 homenx systemd[1]: Started Run anacron jobs.
Sep 21 19:03:11 homenx anacron[12786]: Anacron 2.3 started on 2018-09-21
Sep 21 19:03:11 homenx anacron[12786]: Normal exit (0 jobs run)
Sep 21 19:03:15 homenx kernel: [16331.484410] evdi: [E] evdi_painter_connect:529 Edid length too small
Sep 21 19:03:15 homenx kernel: [16331.484412] evdi: [E] evdi_painter_connect:529 Edid length too small
... x multiple tens of thousands...
The monitor is a Dell 1907FP.

The way to recover was to press numlock, then ctl-alt-F1, F2.. This would temporarily flash the tty console before reblanking all the monitors. After attempting to re-connect to the GUI tty (which would display nothing but a solid cursor line), the following attempt to tty0 would not blank. The evdi controlled monitor would be black, the rest would display a normal console tty0, and a log-in would work normally. Lightdm /lxde/lubuntu was crashed at that point. Console operations were normal.

I tried it with the 4.2.29 driver native. I downloaded the git version, set it up with dkms, same thing. I signed it and rebooted with the secure boot, same thing. The monitor controlled by the display link is a dell at 1280x1024 resolution. DVI-I-2-2 connected 1280x1024+2960+1076 (normal left inverted right x axis y axis) 376mm x 301mm 1280x1024 60.02*+ 75.02
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