[Bug 102322] System crashes after "[drm] IP block:gmc_v8_0 is hung!" / [drm] IP block:sdma_v3_0 is hung!

[bugzilla-daemon at freedesktop.org]

https://bugs.freedesktop.org/show_bug.cgi?id=102322

--- Comment #39 from Andrey Grodzovsky <andrey.grodzovsky at amd.com> ---
(In reply to dwagner from comment #37)
> In the related bug report
> (https://bugs.freedesktop.org/show_bug.cgi?id=107152) I noticed that this
> bug can be triggered very reliably and quickly by playing a video with a
> deliberately lowered frame rate:
>  "mpv --no-correct-pts --fps=3 --ao=null some_arbitrary_video.webm"

> 
> This led me to assume this bug might be caused by the dynamic power
> management, that often ramps performance up/down when a video is played at
> such a low frame rate.

I tried exactly the same - reproduce with same card model and latest kernel and
run webm clip with mpv same way you did and it didn't happen. 

> 
> And indeed, I found this confirmed by many experiments: If I use a script
> like
> > #!/bin/bash
> > cd /sys/class/drm/card0/device
> > echo manual >power_dpm_force_performance_level
> > # low
> > echo 0 >pp_dpm_mclk 
> > echo 0 >pp_dpm_sclk
> > # medium
> > #echo 1 >pp_dpm_mclk 
> > #echo 1 >pp_dpm_sclk
> > # high
> > #echo 1 >pp_dpm_mclk 
> > #echo 6 >pp_dpm_sclk
> to enforce just any performance level, then the crashes do not occur anymore
> - also with the "low frame rate video test".
> 
> So it seems that the transition from one "dpm" performance level to another,
> with a certain probability, causes these crashes. And the more often the
> transitions occur, the sooner one will experience them.
> 
> (BTW: For unknown reason, invoking "xrandr" or enabling a monitor after
> sleep causes the above settings to get lost, so one has to invoke above
> script again.)

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