Re: [PATCH 4/9] drm/i915/vrr: Use set_context_latency instead of intel_vrr_real_vblank_delay()

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

On Sun, Sep 21, 2025 at 10:05:30AM +0530, Ankit Nautiyal wrote:
> The helper intel_vrr_real_vblank_delay() was added to account for the
> SCL lines for TGL where we do not have the TRANS_SET_CONTEXT_LATENCY.
> 
> Now, since we already are tracking the SCL with new member
> `set_context_latency` use it directly instead of the helper.
> 
> Signed-off-by: Ankit Nautiyal <ankit.k.nautiyal@intel.com>

Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>

I think right after this patch you could also do a patch to 
change the guardband calculation to something like:

guardband = vmin - crtc_vdisplay -
	intel_vrr_extra_vblank_delay() -
	crtc_state->set_context_latency;

That better reflects how the hardware opearates.

> ---
>  drivers/gpu/drm/i915/display/intel_vrr.c | 16 +++++-----------
>  1 file changed, 5 insertions(+), 11 deletions(-)
> 
> diff --git a/drivers/gpu/drm/i915/display/intel_vrr.c b/drivers/gpu/drm/i915/display/intel_vrr.c
> index 9e007aab1452..698b33b5b326 100644
> --- a/drivers/gpu/drm/i915/display/intel_vrr.c
> +++ b/drivers/gpu/drm/i915/display/intel_vrr.c
> @@ -79,12 +79,6 @@ intel_vrr_check_modeset(struct intel_atomic_state *state)
>  	}
>  }
>  
> -static int intel_vrr_real_vblank_delay(const struct intel_crtc_state *crtc_state)
> -{
> -	return crtc_state->hw.adjusted_mode.crtc_vblank_start -
> -		crtc_state->hw.adjusted_mode.crtc_vdisplay;
> -}
> -
>  static int intel_vrr_extra_vblank_delay(struct intel_display *display)
>  {
>  	/*
> @@ -102,7 +96,7 @@ int intel_vrr_vblank_delay(const struct intel_crtc_state *crtc_state)
>  {
>  	struct intel_display *display = to_intel_display(crtc_state);
>  
> -	return intel_vrr_real_vblank_delay(crtc_state) +
> +	return crtc_state->set_context_latency +
>  		intel_vrr_extra_vblank_delay(display);
>  }
>  
> @@ -263,7 +257,7 @@ static int intel_vrr_hw_value(const struct intel_crtc_state *crtc_state,
>  	if (DISPLAY_VER(display) >= 13)
>  		return value;
>  	else
> -		return value - intel_vrr_real_vblank_delay(crtc_state);
> +		return value - crtc_state->set_context_latency;
>  }
>  
>  /*
> @@ -761,9 +755,9 @@ void intel_vrr_get_config(struct intel_crtc_state *crtc_state)
>  
>  		if (DISPLAY_VER(display) < 13) {
>  			/* undo what intel_vrr_hw_value() does when writing the values */
> -			crtc_state->vrr.flipline += intel_vrr_real_vblank_delay(crtc_state);
> -			crtc_state->vrr.vmax += intel_vrr_real_vblank_delay(crtc_state);
> -			crtc_state->vrr.vmin += intel_vrr_real_vblank_delay(crtc_state);
> +			crtc_state->vrr.flipline += crtc_state->set_context_latency;
> +			crtc_state->vrr.vmax += crtc_state->set_context_latency;
> +			crtc_state->vrr.vmin += crtc_state->set_context_latency;
>  
>  			crtc_state->vrr.vmin += intel_vrr_vmin_flipline_offset(display);
>  		}
> -- 
> 2.45.2

-- 
Ville Syrjälä
Intel