Re: [PATCH] drm/i915/psr: Request modeset on initial commit to compute PSR state

["Ville Syrjälä" <ville.syrjala@linux.intel.com>]

On Tue, Jan 23, 2024 at 07:57:00AM +0000, Hogander, Jouni wrote:
> On Tue, 2024-01-23 at 09:41 +0200, Ville Syrjälä wrote:
> > On Tue, Jan 23, 2024 at 09:11:03AM +0200, Jouni Högander wrote:
> > > We want to request full modeset in initial fast check to force PSR
> > > state
> > > computation. Otherwise PSR is not enabled on initial commit but on
> > > first
> > > commit with modeset or fastset. With this change Initial commit
> > > will still
> > > end up using fastset (unless something else requires full modeset)
> > > as PSR
> > > parameters are not anymore part of intel_pipe_config_compare.
> > 
> > I think I'd prefer to go the oppostie direction and try to get all
> > the full modeset stuff out from the initial commit. The only reason
> > the initial commit was introduced was to compute the plane states
> > due to lack of readout, and then it got extended due to various other
> > hacks. Our goal is to inherit the state from the BIOS so ideally
> > the whole initial_commit thing wouldn't even exist.
> 
> Bios doesn't enable PSR. Do you think this would be better approach ?:
> 
> https://patchwork.freedesktop.org/patch/575368/?series=129023&rev=1
> 
> What we just need is something triggering intel_psr_compute_config +
> psr enable. Maybe that could be separate function doing both and call
> that from intel_initial_commit. If/when we get rid of that
> intel_initial_commit: this function would be called by that new thing.

I don't think we should do anything at all. PSR will get enabled by the
first proper commit, if possible.

> 
> BR,
> 
> Jouni Högander
> 
> > 
> > > 
> > > Cc: Stanislav Lisovskiy <stanislav.lisovskiy@intel.com>
> > > 
> > > Fixes: a480dd59fe25 ("drm/i915/display: No need for full modeset
> > > due to psr")
> > > Signed-off-by: Jouni Högander <jouni.hogander@intel.com>
> > > ---
> > >  drivers/gpu/drm/i915/display/intel_dp.c  | 8 ++++++++
> > >  drivers/gpu/drm/i915/display/intel_psr.c | 3 ---
> > >  drivers/gpu/drm/i915/display/intel_psr.h | 3 +++
> > >  3 files changed, 11 insertions(+), 3 deletions(-)
> > > 
> > > diff --git a/drivers/gpu/drm/i915/display/intel_dp.c
> > > b/drivers/gpu/drm/i915/display/intel_dp.c
> > > index ab415f41924d..143981b91e8b 100644
> > > --- a/drivers/gpu/drm/i915/display/intel_dp.c
> > > +++ b/drivers/gpu/drm/i915/display/intel_dp.c
> > > @@ -3326,6 +3326,14 @@ 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",
> > > +                           encoder->base.base.id, encoder-
> > > >base.name);
> > > +               crtc_state->uapi.mode_changed = true;
> > > +               fastset = false;
> > > +       }
> > > +
> > >         return fastset;
> > >  }
> > >  
> > > diff --git a/drivers/gpu/drm/i915/display/intel_psr.c
> > > b/drivers/gpu/drm/i915/display/intel_psr.c
> > > index 1010b8c405df..b6db7dbfaf1a 100644
> > > --- a/drivers/gpu/drm/i915/display/intel_psr.c
> > > +++ b/drivers/gpu/drm/i915/display/intel_psr.c
> > > @@ -173,9 +173,6 @@
> > >   * irrelevant for normal operation.
> > >   */
> > >  
> > > -#define CAN_PSR(intel_dp) ((intel_dp)->psr.sink_support && \
> > > -                          (intel_dp)->psr.source_support)
> > > -
> > >  #define CAN_PANEL_REPLAY(intel_dp) ((intel_dp)-
> > > >psr.sink_panel_replay_support && \
> > >                                     (intel_dp)-
> > > >psr.source_panel_replay_support)
> > >  
> > > diff --git a/drivers/gpu/drm/i915/display/intel_psr.h
> > > b/drivers/gpu/drm/i915/display/intel_psr.h
> > > index cde781df84d5..3d9920ebafab 100644
> > > --- a/drivers/gpu/drm/i915/display/intel_psr.h
> > > +++ b/drivers/gpu/drm/i915/display/intel_psr.h
> > > @@ -21,6 +21,9 @@ struct intel_encoder;
> > >  struct intel_plane;
> > >  struct intel_plane_state;
> > >  
> > > +#define CAN_PSR(intel_dp) ((intel_dp)->psr.sink_support && \
> > > +                          (intel_dp)->psr.source_support)
> > > +
> > >  bool intel_encoder_can_psr(struct intel_encoder *encoder);
> > >  void intel_psr_init_dpcd(struct intel_dp *intel_dp);
> > >  void intel_psr_pre_plane_update(struct intel_atomic_state *state,
> > > -- 
> > > 2.34.1
> > 
> 

-- 
Ville Syrjälä
Intel