[PATCH 08/21] drm/amd/display: Fix bug that causes black screen

[Harry Wentland]

From: Anthony Koo <Anthony.Koo at amd.com>

Ignore MSA bit on DP display is usually set during SetTimings, but
there was a case where the module thought refresh rate was not valid
and ignore MSA bit was not set.

Later, a valid refresh rate range was requested but since ignore MSA bit
not set, it caused black screen.

Issue if with how the module checked for VRR support. Fix up that logic.
DM should call new valid_range function to determine if timing is supported.

Signed-off-by: Anthony Koo <Anthony.Koo at amd.com>
Reviewed-by: Aric Cyr <Aric.Cyr at amd.com>
Acked-by: Harry Wentland <harry.wentland at amd.com>
---
 .../gpu/drm/amd/display/modules/freesync/freesync.c    | 18 ++++++------------
 1 file changed, 6 insertions(+), 12 deletions(-)

diff --git a/drivers/gpu/drm/amd/display/modules/freesync/freesync.c b/drivers/gpu/drm/amd/display/modules/freesync/freesync.c
index be6a6c63b4cc..4887c888bbe7 100644
--- a/drivers/gpu/drm/amd/display/modules/freesync/freesync.c
+++ b/drivers/gpu/drm/amd/display/modules/freesync/freesync.c
@@ -613,7 +613,6 @@ void mod_freesync_build_vrr_params(struct mod_freesync *mod_freesync,
 {
 	struct core_freesync *core_freesync = NULL;
 	unsigned long long nominal_field_rate_in_uhz = 0;
-	bool nominal_field_rate_in_range = true;
 	unsigned int refresh_range = 0;
 	unsigned int min_refresh_in_uhz = 0;
 	unsigned int max_refresh_in_uhz = 0;
@@ -638,15 +637,6 @@ void mod_freesync_build_vrr_params(struct mod_freesync *mod_freesync,
 	if (max_refresh_in_uhz > nominal_field_rate_in_uhz)
 		max_refresh_in_uhz = nominal_field_rate_in_uhz;
 
-	/* Allow for some rounding error of actual video timing by taking ceil.
-	 * For example, 144 Hz mode timing may actually be 143.xxx Hz when
-	 * calculated from pixel rate and vertical/horizontal totals, but
-	 * this should be allowed instead of blocking FreeSync.
-	 */
-	if ((min_refresh_in_uhz / 1000000) >
-			((nominal_field_rate_in_uhz + 1000000 - 1) / 1000000))
-		nominal_field_rate_in_range = false;
-
 	// Full range may be larger than current video timing, so cap at nominal
 	if (min_refresh_in_uhz > nominal_field_rate_in_uhz)
 		min_refresh_in_uhz = nominal_field_rate_in_uhz;
@@ -658,10 +648,14 @@ void mod_freesync_build_vrr_params(struct mod_freesync *mod_freesync,
 
 	in_out_vrr->state = in_config->state;
 
-	if ((in_config->state == VRR_STATE_UNSUPPORTED) ||
-				(!nominal_field_rate_in_range)) {
+	if (in_config->state == VRR_STATE_UNSUPPORTED) {
 		in_out_vrr->state = VRR_STATE_UNSUPPORTED;
 		in_out_vrr->supported = false;
+		in_out_vrr->adjust.v_total_min = stream->timing.v_total;
+		in_out_vrr->adjust.v_total_max = stream->timing.v_total;
+
+		return;
+
 	} else {
 		in_out_vrr->min_refresh_in_uhz = min_refresh_in_uhz;
 		in_out_vrr->max_duration_in_us =
-- 
2.15.1