[BUG] drm/panthor: intermittent freezes in Xorg xserver

[BUG] drm/panthor: intermittent freezes in Xorg xserver

[Marius Dinu]

Hi.

The system is Radxa Rock 5 ITX, RK3588, 32GB RAM,
mainline kernel v7.1.0 with panthor driver, mesa 26.0.7 with panfrost driver,
xorg-server v21.1.22 accelerated by modesetting driver, x11perf v1.7.0.

The most clean way to reproduce this bug:
Form a console or ssh session, start Xorg in background, without a window
manager, and then run x11perf on that display.

Xorg :0 &
x11perf -all -display :0

The bug: weird intermittent performance issues in some of the tests.
Examples:

    1000 reps @  18.0799 msec (    55.3/sec): 10x10 rectangle outline
    1000 reps @  18.0791 msec (    55.3/sec): 10x10 rectangle outline
    1000 reps @  18.0790 msec (    55.3/sec): 10x10 rectangle outline
    1000 reps @  18.0789 msec (    55.3/sec): 10x10 rectangle outline
    1000 reps @   0.0287 msec ( 34800.0/sec): 10x10 rectangle outline
    5000 trep @  14.4691 msec (    69.1/sec): 10x10 rectangle outline

 5000000 reps @   0.0029 msec (345000.0/sec): 1-pixel solid circle
 5000000 reps @   0.0009 msec (1100000.0/sec): 1-pixel solid circle
 5000000 reps @   0.0012 msec (818000.0/sec): 1-pixel solid circle
 5000000 reps @   0.0000 msec (20900000.0/sec): 1-pixel solid circle
 5000000 reps @   0.0000 msec (32300000.0/sec): 1-pixel solid circle
25000000 trep @   0.0010 msec (979000.0/sec): 1-pixel solid circle

    1000 reps @  31.6607 msec (    31.6/sec): Fill 10x10 trapezoid
    1000 reps @  16.9012 msec (    59.2/sec): Fill 10x10 trapezoid
    1000 reps @   0.0234 msec ( 42700.0/sec): Fill 10x10 trapezoid
    1000 reps @   0.0272 msec ( 36700.0/sec): Fill 10x10 trapezoid
    1000 reps @  32.1268 msec (    31.1/sec): Fill 10x10 trapezoid
    5000 trep @  16.1479 msec (    61.9/sec): Fill 10x10 trapezoid

There are no messages in kernel log or Xorg log.

Visually, most of the tests runs fast as expected, but in some of the tests
it gets "stuck" randomly. The test suddenly freezes while drawing the pattern.
Then, after a while (a few seconds up to a couple of minutes), it gets
unstuck by itself, draws a few more patterns extremely fast for less than a
second, and then it gets stuck again.
The small test patterns (10px) are a lot more often affected than large
patterns (100px or more).

The bug can also be seen by trying to move or resize windows.
Setting governors to "performance" for the CPU and/or GPU has no effect.

I'm available for tests.
Thanks.

Marius Dinu


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