[PATCH] drm/amd/display: Keep the nominal vtotal while VRR is inactive

[PATCH] drm/amd/display: Keep the nominal vtotal while VRR is inactive

[Matthew Schwartz]

Commit 33c995709121 ("drm/amd/display: Allow VRR params change if
unsynced with the stream") derives the inactive vtotal from
max_refresh_in_uhz and rounds it up. The round trip through integer
rates can add a line even with VRR off. The ASUS ROG Xbox Ally X20's
120.0004 Hz mode exceeds its 120 Hz EDID maximum, so 1152 lines
become 1153 and the CRTC vblank counter measures 119.89 Hz.

Take both limits from stream->timing.v_total, as
mod_freesync_build_vrr_params() does, which keeps the resync to the
stream's timing. Active VRR keeps the helper's rounding.

Fixes: 33c995709121 ("drm/amd/display: Allow VRR params change if unsynced with the stream")
Signed-off-by: Matthew Schwartz <matthew.schwartz@linux.dev>
---
 drivers/gpu/drm/amd/display/modules/freesync/freesync.c | 6 ++----
 1 file changed, 2 insertions(+), 4 deletions(-)

diff --git a/drivers/gpu/drm/amd/display/modules/freesync/freesync.c b/drivers/gpu/drm/amd/display/modules/freesync/freesync.c
index 4bd060e30799..f154a619b533 100644
--- a/drivers/gpu/drm/amd/display/modules/freesync/freesync.c
+++ b/drivers/gpu/drm/amd/display/modules/freesync/freesync.c
@@ -1281,10 +1281,8 @@ void mod_freesync_handle_v_update(struct mod_freesync *mod_freesync,
 	 * If VRR is inactive, set vtotal min and max to nominal vtotal
 	 */
 	 if (in_out_vrr->state == VRR_STATE_INACTIVE) {
-		in_out_vrr->adjust.v_total_min =
-			mod_freesync_calc_v_total_from_refresh(stream,
-				in_out_vrr->max_refresh_in_uhz);
-		in_out_vrr->adjust.v_total_max = in_out_vrr->adjust.v_total_min;
+		in_out_vrr->adjust.v_total_min = stream->timing.v_total;
+		in_out_vrr->adjust.v_total_max = stream->timing.v_total;
 		return;
 	}
 }
-- 
2.56.0