drm/amd/display: Proper return of result when aux engine acquire fails

[Why]
When aux engine acquire fails, we missed populating the operation_result
that describes the failure reason.

[How]
Set operation_result to new type:
AUX_CHANNEL_OPERATION_FAILED_ENGINE_ACQUIRE
in the case aux engine acquire has failed.
Signed-off-by: Anthony Koo <Anthony.Koo@amd.com>
Reviewed-by: Aric Cyr <Aric.Cyr@amd.com>
Acked-by: Leo Li <sunpeng.li@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

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

@@ -113,6 +113,7 @@ static ssize_t dm_dp_aux_transfer(struct drm_dp_aux *aux,
 			result = -EIO;
 			break;
 		case AUX_CHANNEL_OPERATION_FAILED_INVALID_REPLY:
+		case AUX_CHANNEL_OPERATION_FAILED_ENGINE_ACQUIRE:
 			result = -EBUSY;
 			break;
 		case AUX_CHANNEL_OPERATION_FAILED_TIMEOUT:

drivers/gpu/drm/amd/display/dc/dc_ddc_types.h

@@ -49,7 +49,8 @@ enum aux_channel_operation_result {
 	AUX_CHANNEL_OPERATION_FAILED_REASON_UNKNOWN,
 	AUX_CHANNEL_OPERATION_FAILED_INVALID_REPLY,
 	AUX_CHANNEL_OPERATION_FAILED_TIMEOUT,
-	AUX_CHANNEL_OPERATION_FAILED_HPD_DISCON
+	AUX_CHANNEL_OPERATION_FAILED_HPD_DISCON,
+	AUX_CHANNEL_OPERATION_FAILED_ENGINE_ACQUIRE
 };
 
 

drivers/gpu/drm/amd/display/dc/dce/dce_aux.c

@@ -538,8 +538,10 @@ int dce_aux_transfer_raw(struct ddc_service *ddc,
 	memset(&aux_rep, 0, sizeof(aux_rep));
 
 	aux_engine = ddc->ctx->dc->res_pool->engines[ddc_pin->pin_data->en];
-	if (!acquire(aux_engine, ddc_pin))
+	if (!acquire(aux_engine, ddc_pin)) {
+		*operation_result = AUX_CHANNEL_OPERATION_FAILED_ENGINE_ACQUIRE;
 		return -1;
+	}
 
 	if (payload->i2c_over_aux)
 		aux_req.type = AUX_TRANSACTION_TYPE_I2C;
@@ -663,6 +665,7 @@ bool dce_aux_transfer_with_retries(struct ddc_service *ddc,
 			break;
 
 		case AUX_CHANNEL_OPERATION_FAILED_HPD_DISCON:
+		case AUX_CHANNEL_OPERATION_FAILED_ENGINE_ACQUIRE:
 		case AUX_CHANNEL_OPERATION_FAILED_REASON_UNKNOWN:
 		default:
 			goto fail;