Re: [PATCH 01/18] drm/i915: Extract intel_crtc_vblank_delay()

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

On Fri, Jan 03, 2025 at 04:54:53PM +0530, Nautiyal, Ankit K wrote:
> 
> On 12/11/2024 2:39 AM, Ville Syrjala wrote:
> > From: Ville Syrjälä <ville.syrjala@linux.intel.com>
> >
> > Pull the vblank delay computation into a separate function.
> > We'll need more logic here soon and we don't want to pollute
> > intel_crtc_compute_config() with low level details.
> >
> > Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
> > ---
> >   drivers/gpu/drm/i915/display/intel_display.c | 24 +++++++++++++++-----
> >   1 file changed, 18 insertions(+), 6 deletions(-)
> >
> > diff --git a/drivers/gpu/drm/i915/display/intel_display.c b/drivers/gpu/drm/i915/display/intel_display.c
> > index 8e90e99a25d6..ff907afa6451 100644
> > --- a/drivers/gpu/drm/i915/display/intel_display.c
> > +++ b/drivers/gpu/drm/i915/display/intel_display.c
> > @@ -2610,16 +2610,29 @@ static int intel_crtc_compute_pipe_mode(struct intel_crtc_state *crtc_state)
> >   	return 0;
> >   }
> >   
> > -static bool intel_crtc_needs_wa_14015401596(struct intel_crtc_state *crtc_state)
> > +static bool intel_crtc_needs_wa_14015401596(const struct intel_crtc_state *crtc_state)
> >   {
> >   	struct intel_display *display = to_intel_display(crtc_state);
> > -	const struct drm_display_mode *adjusted_mode = &crtc_state->hw.adjusted_mode;
> >   
> >   	return intel_vrr_possible(crtc_state) && crtc_state->has_psr &&
> > -		adjusted_mode->crtc_vblank_start == adjusted_mode->crtc_vdisplay &&
> >   		IS_DISPLAY_VER(display, 13, 14);
> >   }
> >   
> > +static int intel_crtc_vblank_delay(const struct intel_crtc_state *crtc_state)
> > +{
> > +	struct intel_display *display = to_intel_display(crtc_state);
> > +	int vblank_delay = 0;
> > +
> > +	if (!HAS_DSB(display))
> > +		return 0;
> 
> Is this because W2 window is configured to be non zero only when 
> platforms support DSB and DSB is in use?

It's only a thing for platforms with DSB, and there should be no
need for the extra delay when not using the DSB. I was mildly tempted
to even check i915_params.enable_dsb here, but that can changed
dynamically via debufs which would require us to reconfigure the
vblank delay on the fly (and that we can't currently do).

-- 
Ville Syrjälä
Intel