linux-imx

drm/amd/display: Fix warnings on S3 resume

This is a followup to the following revert:

Rex Zhu    Revert "drm/amd/display: Match actual state during S3
           resume."

Three things needed to be addressed:

1. Potential memory leak on dc_state creation in atomic_check during
   s3 resume
2. Warnings are now seen in dmesg during S3 resume
3. Since dc_state is now created in atomic_check, what the reverted
   patch was addressing needs to be reevaluated.

This change addresses the above:

1. Since the suspend procedure calls drm_atomic_state_clear, our hook
   for releasing the dc_state is called. This frees it before
   atomic_check creates it during resume. The leak does not occur.

2. The dc_crtc/plane_state references kept by the atomic states need to
   be released before calling atomic_check, which warns if they are
   non-null. This is because atomic_check is responsible for creating
   the dc_*_states. This is a special case for S3 resume, since the
   atomic state duplication that occurs during suspend also copies a
   reference to the dc_*_states.

3. See 2. comments are also updated to reflect this.

Reviewed-by: Andrey Grodzovsky <andrey.grodzovsky@amd.com>
Signed-off-by: Leo (Sunpeng) Li <sunpeng.li@amd.com>
Reviewed-by: Harry Wentland <Harry.Wentland@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>