From 87acd7f7deb80abad7d59e5923b4dde7aa23006c Mon Sep 17 00:00:00 2001
From: David Galiffi <David.Galiffi@amd.com>
Date: Thu, 11 Jun 2020 17:36:14 -0400
Subject: drm/amd/display: Compare v_front_porch when checking if streams are
Git-commit: 8582aea20bc5de1fc4f2029e6cde604b2c755c0a
Patch-mainline: v5.9-rc1
References: jsc#SLE-12680, jsc#SLE-12880, jsc#SLE-12882, jsc#SLE-12883, jsc#SLE-13496, jsc#SLE-15322
 synchronizable

[Why]
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.

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

Signed-off-by: David Galiffi <David.Galiffi@amd.com>
Reviewed-by: Jun Lei <Jun.Lei@amd.com>
Acked-by: Rodrigo Siqueira <Rodrigo.Siqueira@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Patrik Jakobsson <pjakobsson@suse.de>
---
 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;
-- 
2.29.2