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

[Rodrigo Siqueira Jordao]

On 3/9/23 14:30, Hamza Mahfooz wrote:

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.mahf...@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(

Reviewed-by: Rodrigo Siqueira <rodrigo.sique...@amd.com>

and pushed to amd-staging-drm-next.

Thanks
Siqueira