Regression in 6.6: trying to set DPMS mode kills radeon (r600)

[Alex Deucher]

On Mon, Dec 18, 2023 at 1:52 PM Holger Hoffstätte
<holger at applied-asynchrony.com> wrote:
>
> On 2023-12-16 18:36, Holger Hoffstätte wrote:
>
> <snip>
> > The affected machine is an older SandyBridge dektop with a fanless
> > r600 Redwood GPU, using the radeon driver. "Recently" - some time
> > after the last few 6.6.x stable updates - it started to die with GPU
> > lockups. I first blamed this on standby/resume - because why not? - but
> > this turned out to be wrong; the real culprit is DPMS.
> >
> > I use xfce-power-manager as "screensaver" to turn off the display after
> > inacitvity. This can be configured in two ways: "suspend" and "poweroff".
> > I've been using "poweroff" since forever without problems, until now.
> >
> > The symptom is that everything works fine until the screensaver kicks in
> > and tries to turn the monitor off, which sends the radeon driver and the GPU
> > into a complete tailspin.
>
> <snip>
>
> > Eventually the screensaver tries to switch off the monitor via DPMS "poweroff" method and
> > this greatly upsets the GPU:
> >
> > Dec 12 20:39:59 ragnarok kernel: radeon 0000:01:00.0: ring 0 stalled for more than 10140msec
> > Dec 12 20:39:59 ragnarok kernel: radeon 0000:01:00.0: GPU lockup (current fence id 0x0000000000000002 last fence id 0x0000000000000003 on ring 0)
>
> In the meantime I have confirmed that all this is still more complicated:
> even using the "suspend" method only works after boot, not after a system suspend
> cycle. Yes, weird but reproducible.
>
> I have tried to chase down the problematic release, and as suspected this
> started to happen with 6.6.5; 6.6.4 is fine.
>
> Based on this information I found the offending commits and reverted them
> in order from 6.6.7, which fixes everything for me:
>
> b0399e22ada0 "drm/amd/display: Remove power sequencing check"
> 45f98fccb1f6 "drm/amd/display: Refactor edp power control"

Those patches are for amdgpu.  From the logs in your original post,
you are using the radeon driver.  They two are completely separate
drivers.  I don't see how those patches could be related.  That code
would never even execute.

Alex