[PATCH 5.15 018/277] drm/amd/display: Add signal type check when verify stream backends same

[Greg Kroah-Hartman]

From: Dale Zhao <dale.zhao@xxxxxxx>

[ Upstream commit 047db281c026de5971cedb5bb486aa29bd16a39d ]

[Why]
For allow eDP hot-plug feature, the stream signal may change to VIRTUAL
when plug-out and back to eDP when plug-in. OS will still setPathMode
with same timing for each plugging, but eDP gets no stream update as we
don't check signal type changing back as keeping it VIRTUAL. It's also
unsafe for future cases that stream signal is switched with same timing.

[How]
Check stream signal type change include previous HDMI signal case.

Reviewed-by: Aric Cyr <Aric.Cyr@xxxxxxx>
Acked-by: Wayne Lin <wayne.lin@xxxxxxx>
Signed-off-by: Dale Zhao <dale.zhao@xxxxxxx>
Tested-by: Daniel Wheeler <daniel.wheeler@xxxxxxx>
Signed-off-by: Alex Deucher <alexander.deucher@xxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
 drivers/gpu/drm/amd/display/dc/core/dc_resource.c | 3 +++
 1 file changed, 3 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 7ae409f7dcf8..108f3854cd2a 100644
--- a/drivers/gpu/drm/amd/display/dc/core/dc_resource.c
+++ b/drivers/gpu/drm/amd/display/dc/core/dc_resource.c
@@ -1599,6 +1599,9 @@ static bool are_stream_backends_same(
 	if (is_timing_changed(stream_a, stream_b))
 		return false;
 
+	if (stream_a->signal != stream_b->signal)
+		return false;
+
 	if (stream_a->dpms_off != stream_b->dpms_off)
 		return false;
 
-- 
2.35.1