[PATCH v2 3/8] drm/i915/vrr: Account for TRANS_PUSH delay

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From: Ville Syrjälä <ville.syrjala@xxxxxxxxxxxxxxx>

When we send a push during vblank the TRANS_PUSH write happens
at some point during a scanline, and the hardware picks it up
on the next scanline. Thus there is up to one extra scanline
of delay between the TRANS_PUSH write and the delayed vblank
triggering. Account for that during intel_dsb_wait_vblank_delay()
so that we are guaranteed to be past the delayed vblank before
we trigger the completion interrupt for the commit.

Signed-off-by: Ville Syrjälä <ville.syrjala@xxxxxxxxxxxxxxx>
---
 drivers/gpu/drm/i915/display/intel_dsb.c | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/i915/display/intel_dsb.c b/drivers/gpu/drm/i915/display/intel_dsb.c
index f8bd6fad0c87..01e3bd385cac 100644
--- a/drivers/gpu/drm/i915/display/intel_dsb.c
+++ b/drivers/gpu/drm/i915/display/intel_dsb.c
@@ -116,7 +116,13 @@ static int dsb_vblank_delay(struct intel_atomic_state *state,
 		intel_pre_commit_crtc_state(state, crtc);
 
 	if (pre_commit_is_vrr_active(state, crtc))
-		return intel_vrr_vblank_delay(crtc_state);
+		/*
+		 * When the push is sent during vblank it will trigger
+		 * on the next scanline, hence we have up to one extra
+		 * scanline until the delayed vblank occurs after
+		 * TRANS_PUSH has been written.
+		 */
+		return intel_vrr_vblank_delay(crtc_state) + 1;
 	else
 		return intel_mode_vblank_delay(&crtc_state->hw.adjusted_mode);
 }
-- 
2.45.3




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