[PATCH 22/28] drm/amd/display: Shift DMUB AUX reply command if necessary

[Ray Wu <ray.wu@amd.com>]

From: Wayne Lin <Wayne.Lin@amd.com>

[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: ead08b95fa50 ("drm/amd/display: Fix race condition in DPIA AUX transfer")
Cc: stable@vger.kernel.org
Reviewed-by: Ray Wu <ray.wu@amd.com>
Signed-off-by: Wayne Lin <Wayne.Lin@amd.com>
Signed-off-by: Ray Wu <ray.wu@amd.com>
---
 drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
index cd6e7aa91040..a59d0ff999e9 100644
--- a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
+++ b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
@@ -12852,8 +12852,11 @@ 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)) {
 
-- 
2.43.0