Re: [PATCH] drm/i915/display: Only fail fastset on PSR2

[Paz Zcharya <pazz@chromium.org>]

On Wed, Nov 01, 2023 at 06:26:47AM +0000, Hogander, Jouni wrote:
> On Tue, 2023-10-31 at 23:21 +0000, Paz Zcharya wrote:
> > Currently, i915 fails fastset if both the sink and the source support
> > any version of PSR and regardless of the configuration setting of the
> > driver (i.e., i915.enable_psr kernel argument). However, the
> > implementation of PSR1 enable sequence is already seamless
> > and works smoothly with fastset. Accordingly, do not fail fastset
> > if PSR2 is not enabled.
> 
> Thank you for the patch. Check similar patch I sent some time ago to
> trybot:
> 
> https://patchwork.freedesktop.org/series/125392/
> 

I missed this patch. I apologize!
This is great work and exactly what we (Google ChromeOS) need.
I think your patch is better than mine, so let's abort my patch
and continue the discussion at series/125392.

By the way, we have verified your patch on two Meteor Lake devices
running ChromeOS and it works smoothly (no flickering or modesets).
I'll comment on the other patch as well.

> If we want to temporarily do this only for psr1 I think you could check
> what I've done in drivers/gpu/drm/i915/display/intel_display.c in my
> patch and modify your patch accordingly. Otherwise e.g. our IGT
> testcases which are toggling PSR enable/disable/psr1/psr2 are to my
> understanding performing full modeset and possible issues are not
> revealed.
> 
> After modifying drivers/gpu/drm/i915/display/intel_display.c you can
> also verify it is really seamless and smooth by toggling different PSR
> states via /sys/kernel/debug/dri/0/i915_edp_psr_debug. That interface
> is performing atomic commit when PSR mode is changed.
> 
> BR,
> 
> Jouni Högander
> > 
> > Signed-off-by: Paz Zcharya <pazz@google.com>
> > ---
> > 
> >  drivers/gpu/drm/i915/display/intel_dp.c  | 4 ++--
> >  drivers/gpu/drm/i915/display/intel_psr.c | 2 +-
> >  drivers/gpu/drm/i915/display/intel_psr.h | 1 +
> >  3 files changed, 4 insertions(+), 3 deletions(-)
> > 
> > diff --git a/drivers/gpu/drm/i915/display/intel_dp.c
> > b/drivers/gpu/drm/i915/display/intel_dp.c
> > index e0e4cb529284..a1af96e31518 100644
> > --- a/drivers/gpu/drm/i915/display/intel_dp.c
> > +++ b/drivers/gpu/drm/i915/display/intel_dp.c
> > @@ -2584,8 +2584,8 @@ bool intel_dp_initial_fastset_check(struct
> > intel_encoder *encoder,
> >                 fastset = false;
> >         }
> >  
> > -       if (CAN_PSR(intel_dp)) {
> > -               drm_dbg_kms(&i915->drm, "[ENCODER:%d:%s] Forcing full
> > modeset to compute PSR state\n",
> > +       if (CAN_PSR(intel_dp) && psr2_global_enabled(intel_dp)) {
> > +               drm_dbg_kms(&i915->drm, "[ENCODER:%d:%s] Forcing full
> > modeset due to PSR2\n",
> >                             encoder->base.base.id, encoder-
> > >base.name);
> >                 crtc_state->uapi.mode_changed = true;
> >                 fastset = false;
> > diff --git a/drivers/gpu/drm/i915/display/intel_psr.c
> > b/drivers/gpu/drm/i915/display/intel_psr.c
> > index 97d5eef10130..388bc3246db9 100644
> > --- a/drivers/gpu/drm/i915/display/intel_psr.c
> > +++ b/drivers/gpu/drm/i915/display/intel_psr.c
> > @@ -187,7 +187,7 @@ static bool psr_global_enabled(struct intel_dp
> > *intel_dp)
> >         }
> >  }
> >  
> > -static bool psr2_global_enabled(struct intel_dp *intel_dp)
> > +bool psr2_global_enabled(struct intel_dp *intel_dp)
> >  {
> >         struct drm_i915_private *i915 = dp_to_i915(intel_dp);
> >  
> > diff --git a/drivers/gpu/drm/i915/display/intel_psr.h
> > b/drivers/gpu/drm/i915/display/intel_psr.h
> > index 0b95e8aa615f..6f3c36389cd3 100644
> > --- a/drivers/gpu/drm/i915/display/intel_psr.h
> > +++ b/drivers/gpu/drm/i915/display/intel_psr.h
> > @@ -21,6 +21,7 @@ struct intel_encoder;
> >  struct intel_plane;
> >  struct intel_plane_state;
> >  
> > +bool psr2_global_enabled(struct intel_dp *intel_dp);
> >  void intel_psr_init_dpcd(struct intel_dp *intel_dp);
> >  void intel_psr_pre_plane_update(struct intel_atomic_state *state,
> >                                 struct intel_crtc *crtc);
> 

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