[PATCH] drm/amd/display: use a more accurate check in dm_helpers_dp_read_dpcd()

[Hamza Mahfooz <hamza.mahfooz@amd.com>]

We should be checking if drm_dp_dpcd_read() returns the size that we are
asking it to read instead of just checking if it is greater than zero.
Also, we should WARN_ON() here since this condition is only ever met, if
there is an issue worth investigating. So, compare the return value of
drm_dp_dpcd_read() to size and WARN_ON() if they aren't equal.

Signed-off-by: Hamza Mahfooz <hamza.mahfooz@amd.com>
---
 drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_helpers.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_helpers.c b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_helpers.c
index 8d598b322e5b..ed2ed7b1d869 100644
--- a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_helpers.c
+++ b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_helpers.c
@@ -511,8 +511,8 @@ bool dm_helpers_dp_read_dpcd(
 		return false;
 	}
 
-	return drm_dp_dpcd_read(&aconnector->dm_dp_aux.aux, address,
-			data, size) > 0;
+	return !WARN_ON(drm_dp_dpcd_read(&aconnector->dm_dp_aux.aux, address,
+					 data, size) != size);
 }
 
 bool dm_helpers_dp_write_dpcd(
-- 
2.39.2