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

[Boris Brezillon]

On Fri, 26 Jun 2026 14:50:17 +0300
Marius Dinu <m95d+git at psihoexpert.ro> wrote:

> 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.

Are we sure that's a panthor issue? Also, is this a regression
introduced by the latest kernel version, or has it been like that from
the start?

Also, would you mind opening an issue on [1]?

> 
> 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.

It smells like a signalling issue. Can you check the CPU activity and
report any outstanding process? Can you maybe connect a gdb to the
x11perf to see where it's blocked, and post the backtrace here (or in
the gitlab issue)?

Regards,

Boris

[1]https://gitlab.freedesktop.org/mesa/mesa