Re: [PATCH v3] drm/i915/alpm: Add a quirk to keep the fast wake ahead of the IO buffer wake

["Hogander, Jouni" <jouni.hogander@intel.com>]

On Fri, 2026-09-04 at 09:32 -0400, Jake Steinman wrote:
> On Fri, 2026-09-04 Jouni Högander wrote:
> > I think PSR2 was working on that setup at the point when I
> > introduced
> > that quirk
> > ...
> > Maybe this is actually matter of bisection?
> 
> Checked that today with a probe that only polls the sink (0x2006,
> 0x2008, 0x200a every 200 ms, error bit cleared after each read), so
> it
> runs the same on any kernel:
> 
>   stock 7.2.2, io/fast 11/11:    CRC error re-latched on every poll,
>                                  0x2008 = 3 throughout,
>                                  0x200a shows SU_VALID in 2 of 94
> polls
>   7.3-rc1, io/fast 11/11:        same, SU_VALID in 7 of 90 polls
>   7.3-rc1, io/fast 11/12:        no CRC errors, 0x2008 = 2,
>                                  SU_VALID never
> 
> So what looks like PSR2 working is the link failing on every wake and
> the engine re-entering over and over. Each re-entry does its two
> entry
> captures, those carry SU_VALID, then the engine parks in SU_STANDBY
> until the next failed wake resets it. Screen updates come from the
> resyncs, not from selective updates. With the wake clean there are no
> resyncs and the panel stays on the stale frame.
> 
> I doubt bisecting finds anything for PSR2: it was in this state in
> April too unless the wake formulas were different then, and
> intel_alpm.c has four commits since March, none touching them. Panel
> Replay uses the aux-less wake, which does not fail, so it froze
> outright from the start. That is the quirk.
> 
> Probe script and logs are on 9119.

Is PSR2 working on your setup with this quirk?

BR,
Jouni Högander

> 
> Jake