Created attachment 142807 [details] dmesg output after trying setting monitor on via xrandr I'm running latest Debian sid/buster on a Dell XPS 9370 laptop (Kabylake-R graphics). I've connected an external DisplayPort monitor to my laptop over USB-C through a Lindy USB 3.1 Type C Docking Station. It works fine it seems normally, the DisplayPort is recognized as DP-2-2 in xrandr. After suspending the laptop, and wake it up again, the monitor is blank, but xrandr says it's still connected and a mode is selected. After setting monitor "--off" and "--auto" again no picture comes up, and I get the errors shown in the attached dmesg.
Hi, Please try to reproduce the error using drm-tip (https://cgit.freedesktop.org/drm-tip) and kernel parameters drm.debug=0x1e log_buf_len=4M, and if the problem persists attach the full dmesg from boot. There has been some fixes lately, eg: https://bugs.freedesktop.org/show_bug.cgi?id=108616 and some others. cc Stan to comment
(In reply to Jani Saarinen from comment #1) > Hi, > Please try to reproduce the error using drm-tip > (https://cgit.freedesktop.org/drm-tip) and kernel parameters drm.debug=0x1e > log_buf_len=4M, and if the problem persists attach the full dmesg from boot. > > There has been some fixes lately, eg: > https://bugs.freedesktop.org/show_bug.cgi?id=108616 and some others. > > cc Stan to comment I have tried latest 4.20-rc6 kernel from drm-tip. After fiddling with the config to make my laptop boot at least properly, but without many drivers for my other hardware in the laptop, I seems it's somewhat working well. When booting with the dock plugged in and monitor on, the monitor shows the boot console as expected, and get recognized as DP-4 by xrandr. After suspending, and resuming, the monitor flashes a bit and shows the image again, but now the monitor is identified as DP-2-2 instead.
Created attachment 142811 [details] xrandr after resume
Created attachment 142812 [details] gzip'ed dmesg with boot params
This looks similar to https://bugs.freedesktop.org/show_bug.cgi?id=106250 actually. Problem is that DP MST each time gets reassigned with a new connector id, which might confuse userspace, depending on timing and luck. Currently there is no official fix, as the fix which I proposed, was told to have some other side effects. However you can try it anyway, just to confirm that this is same kind of bug. So please try a "kernel fix" attached to the bug above. The real fix is to reuse connector ids, which requires some DP MST connector life span changes.
Reporter do you agree as dup of https://bugs.freedesktop.org/show_bug.cgi?id=106250?
Highly likely dup *** This bug has been marked as a duplicate of bug 106250 ***
It really does look like the same issue
*** This bug has been marked as a duplicate of bug 106250 ***
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