[Bug 109522] drm:intel_dp_start_link_train [i915] *ERROR* failed to enable link training

[bugzilla-daemon at freedesktop.org]

https://bugs.freedesktop.org/show_bug.cgi?id=109522

--- Comment #18 from howaboutsynergy at pm.me ---
ok I have another way to reproduce  that bypasses the xrandr run, and it
involves switching step 1 with step 2 in Comment 13. So with this, it doesn't
matter if xrandr is ran in a `while` loop, the -110 will happen nonetheless.
Kernel tested 5.1.10

The monitor is LG(something) and is connected via the DisplayPort to the ASUS
Prime Z370-A motherboard connector and I've no dedicated gfx card, it's using
the integrated one from Intel(R) Core(TM) i7-8700K CPU @ 3.70GHz (oh I see I've
mentioned this in Comment 11 already, the BIOS is the same version still
because the next one is probably trojaned xD)


Ok so to summarize, steps from Comment 13 will only work(to reproduce the
issue) if you're not running xrandr in a while loop like:
$ while true; do (date; cat /proc/uptime; xrandr --verbose --dryrun
--nograb|grep -w 85 -C 2|grep 'link-status: Bad'|| echo "good"); sleep 1; done
but, if you insist on running xrandr like that(or even without --dryrun
--nograb) then simply switching step 1 with step 2(aka run 'monoff' first then
turn off monitor) then xrandr will have no effect and the issue can be
reproduced 100% (or so it seems, to me).

By reproduce the issue I mean:
[ 3946.388708] [drm:intel_dp_set_link_train [i915]] *ERROR* ret=-110 len=5
[ 3946.388736] [drm:intel_dp_start_link_train [i915]] *ERROR* failed to enable
link training
[ 3946.658135] [drm:intel_dp_set_link_train [i915]] *ERROR* ret=-110 len=1
...
[ 3950.951159] [drm:intel_dp_set_link_train [i915]] *ERROR* ret=5 len=5
[ 3950.952869] [drm:intel_dp_set_link_train [i915]] *ERROR* ret=5 len=5
[ 3950.955573] [drm:intel_dp_set_link_train [i915]] *ERROR* ret=1 len=1


And in the case when xrandr is ran in a `while` loop using Comment 13 steps
(without swapping steps 1 and 2), only the last 3 dmesg messages from above
appear, meaning the issue doesn't occurr.

I'm up for trying any patches/tries that you want me to test, even if they
lockup/oops/panic, I have kdump set up and we'll get nice stacktrace and
stuff;-) just like in this bug for example:
https://bugzilla.kernel.org/show_bug.cgi?id=203849

Cheers!

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