[PATCH 25/30] drm/amd/display: Compare v_front_porch when checking if streams are synchronizable

Rodrigo Siqueira Rodrigo.Siqueira at amd.com
Fri Jun 19 20:12:17 UTC 2020

From: David Galiffi <David.Galiffi at amd.com>

If the front porch of the two timings differ, then there may not be
enough time while both streams are in vertical blank to perform a memory
clock change. This can hang the system.

Check the each streams timing.v_front_porch when determining if the two
streams are synchronizable.

Signed-off-by: David Galiffi <David.Galiffi at amd.com>
Reviewed-by: Jun Lei <Jun.Lei at amd.com>
Acked-by: Rodrigo Siqueira <Rodrigo.Siqueira at amd.com>
 drivers/gpu/drm/amd/display/dc/core/dc_resource.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/drivers/gpu/drm/amd/display/dc/core/dc_resource.c b/drivers/gpu/drm/amd/display/dc/core/dc_resource.c
index 3d0003c69373..1000dc6daf72 100644
--- a/drivers/gpu/drm/amd/display/dc/core/dc_resource.c
+++ b/drivers/gpu/drm/amd/display/dc/core/dc_resource.c
@@ -399,6 +399,10 @@ bool resource_are_streams_timing_synchronizable(
 				!= stream2->timing.v_addressable)
 		return false;
+	if (stream1->timing.v_front_porch
+				!= stream2->timing.v_front_porch)
+		return false;
 	if (stream1->timing.pix_clk_100hz
 				!= stream2->timing.pix_clk_100hz)
 		return false;

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