drm/amd/display: 7 retries + 50 ms timeout on AUX DEFER

[WHY]
DP 2.0 SCR specifies that TX devices must retry at least 7 times when
receiving an AUX DEFER reply from RX. In addition, the specification
states that the TX shall not retry indefinitely, and gives a suggestive
timeout interval of 50ms.

[HOW]
Keep retrying until both 7 or more retries have been made, and the 50ms
interval has passed.

Signed-off-by: Wesley Chalmers <[e-mail]>
Reviewed-by: Jun Lei <[e-mail]>
Acked-by: Anson Jacob <[e-mail]>
Tested-by: Daniel Wheeler <[e-mail]>
Signed-off-by: Alex Deucher <[e-mail]>

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

···
 
 #define AUX_MAX_RETRIES 7
 #define AUX_MIN_DEFER_RETRIES 7
+#define AUX_MAX_DEFER_TIMEOUT_MS 50
 #define AUX_MAX_I2C_DEFER_RETRIES 7
 #define AUX_MAX_INVALID_REPLY_RETRIES 2
 #define AUX_MAX_TIMEOUT_RETRIES 3
···
 	bool payload_reply = true;
 	enum aux_return_code_type operation_result;
 	bool retry_on_defer = false;
+	struct ddc *ddc_pin = ddc->ddc_pin;
+	struct dce_aux *aux_engine = ddc->ctx->dc->res_pool->engines[ddc_pin->pin_data->en];
+	struct aux_engine_dce110 *aux110 = FROM_AUX_ENGINE(aux_engine);
+	uint32_t defer_time_in_ms = 0;
 
 	int aux_ack_retries = 0,
 		aux_defer_retries = 0,
···
 			break;
 
 			case AUX_TRANSACTION_REPLY_AUX_DEFER:
+				/* polling_timeout_period is in us */
+				defer_time_in_ms += aux110->polling_timeout_period / 1000;
+				/* fall through */
 			case AUX_TRANSACTION_REPLY_I2C_OVER_AUX_DEFER:
 				retry_on_defer = true;
 				fallthrough;
 			case AUX_TRANSACTION_REPLY_I2C_OVER_AUX_NACK:
-				if (++aux_defer_retries >= AUX_MIN_DEFER_RETRIES) {
+				if (++aux_defer_retries >= AUX_MIN_DEFER_RETRIES
+						&& defer_time_in_ms >= AUX_MAX_DEFER_TIMEOUT_MS) {
 					goto fail;
 				} else {
 					if ((*payload->reply == AUX_TRANSACTION_REPLY_AUX_DEFER) ||
 						(*payload->reply == AUX_TRANSACTION_REPLY_I2C_OVER_AUX_DEFER)) {
-						if (payload->defer_delay > 1)
+						if (payload->defer_delay > 1) {
 							msleep(payload->defer_delay);
-						else if (payload->defer_delay <= 1)
+							defer_time_in_ms += payload->defer_delay;
+						} else if (payload->defer_delay <= 1) {
 							udelay(payload->defer_delay * 1000);
+							defer_time_in_ms += payload->defer_delay;
+						}
 					}
 				}
 				break;