Re: [PATCH v4 09/13] drm/i915/display: Don't use DSB if psr mode changing

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

On Fri, 2025-01-24 at 14:09 +0200, Hogander, Jouni wrote:
> On Fri, 2025-01-24 at 13:53 +0200, Ville Syrjälä wrote:
> > On Fri, Jan 24, 2025 at 12:56:20PM +0200, Jouni Högander wrote:
> > > Changing PSR mode using DSB is not implemented. Do not use DSB
> > > when
> > > PSR
> > > mode is changing.
> > > 
> > > Signed-off-by: Jouni Högander <jouni.hogander@intel.com>
> > > Reviewed-by: Animesh Manna <animesh.manna@intel.com>
> > > ---
> > >  drivers/gpu/drm/i915/display/intel_display.c | 3 ++-
> > >  1 file changed, 2 insertions(+), 1 deletion(-)
> > > 
> > > diff --git a/drivers/gpu/drm/i915/display/intel_display.c
> > > b/drivers/gpu/drm/i915/display/intel_display.c
> > > index 3ac1cc9ac08a8..a189aa437d972 100644
> > > --- a/drivers/gpu/drm/i915/display/intel_display.c
> > > +++ b/drivers/gpu/drm/i915/display/intel_display.c
> > > @@ -7682,7 +7682,8 @@ static void intel_atomic_dsb_finish(struct
> > > intel_atomic_state *state,
> > >  		!new_crtc_state->scaler_state.scaler_users &&
> > >  		!old_crtc_state->scaler_state.scaler_users &&
> > >  		!intel_crtc_needs_modeset(new_crtc_state) &&
> > > -		!intel_crtc_needs_fastset(new_crtc_state);
> > > +		!intel_crtc_needs_fastset(new_crtc_state) &&
> > > +		!intel_psr_is_psr_mode_changing(old_crtc_state,
> > > new_crtc_state);
> > 
> > Hmm. Doesn't all that imply a fastset anyway
> 
> PSR/PR doesn't imply fastset.
> 
> At the time of enabling PSR/PR crtc_state->has_psr is true at this
> point, but PSR is not yet enabled. It gets enabled only in 
> pre_plane_update. Also in hsw_activate_psr2 and
> dg2_panel_replay_activate we are writing PSR2_MAN_TRK_CTL.

I said it wrong here: post_plane_update I mean of course.

BR,

Jouni Högander

> 
> BR,
> 
> Jouni Högander
> 
> > , and/or maybe all the
> > PSR stuff happens in the {pre,post}_plane_update() stuff? In which
> > case it shouldn't really matter for the stuff that the DSB does.
> > 
> > >  
> > >  	if (!new_crtc_state->use_dsb && !new_crtc_state-
> > > > dsb_color_vblank)
> > >  		return;
> > > -- 
> > > 2.43.0
> > 
>