On Wed, Oct 15, 2025 at 12:52:16PM +0530, Ankit Nautiyal wrote: > As we move towards using a shorter, optimized guardband, we need to adjust > how the delayed vblank start is computed. > > Adjust the crtc_vblank_start using Vmin Vtotal - guardband only when > intel_vrr_always_use_vrr_tg() is true. Also update the > pipe_mode->crtc_vblank_start which is derived from > adjusted_mode->crtc_vblank_start in intel_crtc_compute_pipe_mode(). > > To maintain consistency between the computed and readout paths, also update > the readout logic in intel_vrr_get_config() to overwrite crtc_vblank_start > with the same value (vtotal - guardband) on platforms with always-on > VRR TG. pipe_mode is derived > > This also paves way for guardband optimization, by handling the movement of > the crtc_vblank_start for platforms that have VRR TG always active. > > v2: Drop the helper and add the adjustment directly to > intel_vrr_compute_guardband(). (Ville) > v3: Use adjusted_mode.crtc_vtotal instead of vmin and include the readout > logic to keep the compute and readout paths in sync. (Ville) > v4: Also set pipe_mode->crtc_vblank_start as its derived from > adjusted_mode. (Ville) > > Signed-off-by: Ankit Nautiyal <[email protected]> > --- > drivers/gpu/drm/i915/display/intel_vrr.c | 23 ++++++++++++++++++++++- > 1 file changed, 22 insertions(+), 1 deletion(-) > > diff --git a/drivers/gpu/drm/i915/display/intel_vrr.c > b/drivers/gpu/drm/i915/display/intel_vrr.c > index 8d71d7dc9d12..1cfcc31bd899 100644 > --- a/drivers/gpu/drm/i915/display/intel_vrr.c > +++ b/drivers/gpu/drm/i915/display/intel_vrr.c > @@ -436,7 +436,8 @@ intel_vrr_max_guardband(struct intel_crtc_state > *crtc_state) > void intel_vrr_compute_guardband(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; > + struct drm_display_mode *adjusted_mode = &crtc_state->hw.adjusted_mode; > + struct drm_display_mode *pipe_mode = &crtc_state->hw.pipe_mode; > > if (!intel_vrr_possible(crtc_state)) > return; > @@ -444,6 +445,13 @@ void intel_vrr_compute_guardband(struct intel_crtc_state > *crtc_state) > crtc_state->vrr.guardband = min(crtc_state->vrr.vmin - > adjusted_mode->crtc_vdisplay, > intel_vrr_max_guardband(crtc_state)); > > + if (intel_vrr_always_use_vrr_tg(display)) { > + adjusted_mode->crtc_vblank_start = > + adjusted_mode->crtc_vtotal - crtc_state->vrr.guardband;
Maybe a small comment here to explain why we touch pipe_mode. Eg. /* * pipe_mode has already been derived from the * original adjusted_mode, keep the two in sync. */ Reviewed-by: Ville Syrjälä <[email protected]> > + pipe_mode->crtc_vblank_start = > + adjusted_mode->crtc_vblank_start; > + } > + > if (DISPLAY_VER(display) < 13) > crtc_state->vrr.pipeline_full = > intel_vrr_guardband_to_pipeline_full(crtc_state, > @@ -821,6 +829,19 @@ void intel_vrr_get_config(struct intel_crtc_state > *crtc_state) > */ > if (crtc_state->vrr.enable) > crtc_state->mode_flags |= I915_MODE_FLAG_VRR; > + > + /* > + * For platforms that always use the VRR timing generator, we overwrite > + * crtc_vblank_start with vtotal - guardband to reflect the delayed > + * vblank start. This works for both default and optimized guardband > values. > + * On other platforms, we keep the original value from > + * intel_get_transcoder_timings() and apply adjustments only in > VRR-specific > + * paths as needed. > + */ > + if (intel_vrr_always_use_vrr_tg(display)) > + crtc_state->hw.adjusted_mode.crtc_vblank_start = > + crtc_state->hw.adjusted_mode.crtc_vtotal - > + crtc_state->vrr.guardband; > } > > int intel_vrr_safe_window_start(const struct intel_crtc_state *crtc_state) > -- > 2.45.2 -- Ville Syrjälä Intel
