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

[Marius Dinu <m95d+git@psihoexpert.ro>]

On Mon, 2026-06-29 09.44.19 ++0200, Boris Brezillon wrote:
> On Fri, 26 Jun 2026 14:50:17 +0300
> Marius Dinu <m95d+git@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?

It was from the start, not a regression. I think I started from v6.18 on this
board IIRC. If you need me to test earlier versions, say so.

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

I already did.
https://gitlab.freedesktop.org/mesa/mesa/-/work_items/15721

> > 
> > 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)?
> 

x11perf is waiting on I/O (red "D" in htop). CPU is completely idle, not even
grey "io-wait" activity.

I have no experience using gdb. Please give me the exact command to run.

> Regards,
> 
> Boris
> 
> [1]https://gitlab.freedesktop.org/mesa/mesa

Marius


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