drm/amd/display: Shift DMUB AUX reply command if necessary

[Why]
Defined value of dmub AUX reply command field get updated but didn't
adjust dm receiving side accordingly.

[How]
Check the received reply command value to see if it's updated version
or not. Adjust it if necessary.

Fixes: ead08b9 ("drm/amd/display: Fix race condition in DPIA AUX transfer")
Cc: Mario Limonciello <[email protected]>
Cc: Alex Deucher <[email protected]>
Reviewed-by: Ray Wu <[email protected]>
Signed-off-by: Wayne Lin <[email protected]>
Signed-off-by: Ray Wu <[email protected]>
Tested-by: Daniel Wheeler <[email protected]>
Signed-off-by: Alex Deucher <[email protected]>

Author: Wayne Lin

drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c

@@ -12848,8 +12848,11 @@ int amdgpu_dm_process_dmub_aux_transfer_sync(
 		goto out;
 	}
 
+	payload->reply[0] = adev->dm.dmub_notify->aux_reply.command & 0xF;
+	if (adev->dm.dmub_notify->aux_reply.command & 0xF0)
+		/* The reply is stored in the top nibble of the command. */
+		payload->reply[0] = (adev->dm.dmub_notify->aux_reply.command >> 4) & 0xF;
 
-	payload->reply[0] = adev->dm.dmub_notify->aux_reply.command;
 	if (!payload->write && p_notify->aux_reply.length &&
 			(payload->reply[0] == AUX_TRANSACTION_REPLY_AUX_ACK)) {