drm/amd/display: Add signal type check when verify stream backends same

stable inclusion
from stable-v5.10.111
commit 85313d9bc7bd1f20d4ff92023fe731dadf0c778f
category: bugfix
bugzilla: https://gitee.com/openeuler/kernel/issues/I5GL1Z

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=85313d9bc7bd1f20d4ff92023fe731dadf0c778f

--------------------------------

[ Upstream commit 047db281 ]

[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: NAric Cyr <Aric.Cyr@amd.com>
Acked-by: NWayne Lin <wayne.lin@amd.com>
Signed-off-by: NDale Zhao <dale.zhao@amd.com>
Tested-by: NDaniel Wheeler <daniel.wheeler@amd.com>
Signed-off-by: NAlex Deucher <alexander.deucher@amd.com>
Signed-off-by: NSasha Levin <sashal@kernel.org>
Signed-off-by: NZheng Zengkai <zhengzengkai@huawei.com>
Reviewed-by: NWei Li <liwei391@huawei.com>

drivers/gpu/drm/amd/display/dc/core/dc_resource.c

@@ -1674,6 +1674,9 @@ 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;