Re: [PATCH 1/5] drm/i915/psr: Add helper to get min psr guardband

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

On Fri, 2025-10-17 at 09:07 +0000, Hogander, Jouni wrote:
> On Fri, 2025-10-17 at 10:31 +0530, Ankit Nautiyal wrote:
> > Introduce a helper to compute the max link wake latency when using
> > Auxless/Aux wake mechanism for PSR/Panel Replay/LOBF features.
> > 
> > This will be used to compute the minimum guardband so that the link
> > wake
> > latencies are accounted and these features work smoothly for higher
> > refresh rate panels.
> > 
> > Bspec: 70151, 71477
> > Signed-off-by: Ankit Nautiyal <ankit.k.nautiyal@intel.com>
> > ---
> >  drivers/gpu/drm/i915/display/intel_psr.c | 12 ++++++++++++
> >  drivers/gpu/drm/i915/display/intel_psr.h |  1 +
> >  2 files changed, 13 insertions(+)
> > 
> > diff --git a/drivers/gpu/drm/i915/display/intel_psr.c
> > b/drivers/gpu/drm/i915/display/intel_psr.c
> > index 703e5f6af04c..a8303b669853 100644
> > --- a/drivers/gpu/drm/i915/display/intel_psr.c
> > +++ b/drivers/gpu/drm/i915/display/intel_psr.c
> > @@ -4416,3 +4416,15 @@ void intel_psr_compute_config_late(struct
> > intel_dp *intel_dp,
> >  
> >  	intel_psr_set_non_psr_pipes(intel_dp, crtc_state);
> >  }
> > +
> > +int intel_psr_min_guardband(struct intel_crtc_state *crtc_state)
> > +{
> > +	struct intel_display *display =
> > to_intel_display(crtc_state);
> > +	int auxless_wake_lines = crtc_state-
> > > alpm_state.aux_less_wake_lines;
> > +	int wake_lines = DISPLAY_VER(display) < 20 ?
> > +			 psr2_block_count_lines(crtc_state-
> > > alpm_state.io_wake_lines,
> > +						crtc_state-
> > > alpm_state.fast_wake_lines) :
> > +			 crtc_state->alpm_state.io_wake_lines;
> > +
> > +	return max(auxless_wake_lines, wake_lines);
> 
> hmm, now if you add:
> 
> if (crtc_state->req_psr2_sdp_prior_scanline)
> 		psr_min_guardband++;
> 
> Whatever is the PSR mode it can be enabled what comes to vblank
> restrictions and you can drop psr_compute_config_late?

also this should be added to remove psr_compute_config_late:

        psr_min_guardband += _intel_psr_min_set_context_latency(crtc_state,
						     crtc_state->has_panel_replay,
						     crtc_state->has_sel_update);

BR,

Jouni Högander

> 
> BR,
> 
> Jouni Högander
> 
> > +}
> > diff --git a/drivers/gpu/drm/i915/display/intel_psr.h
> > b/drivers/gpu/drm/i915/display/intel_psr.h
> > index b17ce312dc37..620b35928832 100644
> > --- a/drivers/gpu/drm/i915/display/intel_psr.h
> > +++ b/drivers/gpu/drm/i915/display/intel_psr.h
> > @@ -85,5 +85,6 @@ bool intel_psr_needs_alpm_aux_less(struct
> > intel_dp
> > *intel_dp,
> >  				   const struct intel_crtc_state
> > *crtc_state);
> >  void intel_psr_compute_config_late(struct intel_dp *intel_dp,
> >  				   struct intel_crtc_state
> > *crtc_state);
> > +int intel_psr_min_guardband(struct intel_crtc_state *crtc_state);
> >  
> >  #endif /* __INTEL_PSR_H__ */
>