drm/amd/display: AUX will exit when HPD LOW detected

This change shorten wait time when HPD LOW. With HPD LOW, without this
change, AUX routine delay is 450us. With this change, it is 42us.

Signed-off-by: Hersen Wu <hersenxs.wu@amd.com>
Reviewed-by: Tony Cheng <Tony.Cheng@amd.com>
Reviewed-by: Harry Wentland <Harry.Wentland@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

drivers/gpu/drm/amd/display/dc/i2caux/aux_engine.c

@@ -157,6 +157,10 @@ static void process_read_reply(
 			ctx->operation_succeeded = false;
 		}
 	break;
+	case AUX_TRANSACTION_REPLY_HPD_DISCON:
+		ctx->status = I2CAUX_TRANSACTION_STATUS_FAILED_HPD_DISCON;
+		ctx->operation_succeeded = false;
+	break;
 	default:
 		ctx->status = I2CAUX_TRANSACTION_STATUS_UNKNOWN;
 		ctx->operation_succeeded = false;
@@ -215,6 +219,10 @@ static void process_read_request(
 			 * so we should not wait here */
 		}
 	break;
+	case AUX_CHANNEL_OPERATION_FAILED_HPD_DISCON:
+		ctx->status = I2CAUX_TRANSACTION_STATUS_FAILED_HPD_DISCON;
+		ctx->operation_succeeded = false;
+	break;
 	default:
 		ctx->status = I2CAUX_TRANSACTION_STATUS_UNKNOWN;
 		ctx->operation_succeeded = false;
@@ -370,6 +378,10 @@ static void process_write_reply(
 			ctx->operation_succeeded = false;
 		}
 	break;
+	case AUX_TRANSACTION_REPLY_HPD_DISCON:
+		ctx->status = I2CAUX_TRANSACTION_STATUS_FAILED_HPD_DISCON;
+		ctx->operation_succeeded = false;
+	break;
 	default:
 		ctx->status = I2CAUX_TRANSACTION_STATUS_UNKNOWN;
 		ctx->operation_succeeded = false;
@@ -422,6 +434,10 @@ static void process_write_request(
 			 * so we should not wait here */
 		}
 	break;
+	case AUX_CHANNEL_OPERATION_FAILED_HPD_DISCON:
+		ctx->status = I2CAUX_TRANSACTION_STATUS_FAILED_HPD_DISCON;
+		ctx->operation_succeeded = false;
+	break;
 	default:
 		ctx->status = I2CAUX_TRANSACTION_STATUS_UNKNOWN;
 		ctx->operation_succeeded = false;

drivers/gpu/drm/amd/display/dc/i2caux/aux_engine.h

@@ -51,6 +51,8 @@ enum aux_transaction_reply {
 	AUX_TRANSACTION_REPLY_I2C_NACK = 0x10,
 	AUX_TRANSACTION_REPLY_I2C_DEFER = 0x20,
 
+	AUX_TRANSACTION_REPLY_HPD_DISCON = 0x40,
+
 	AUX_TRANSACTION_REPLY_INVALID = 0xFF
 };
 
@@ -64,7 +66,8 @@ enum aux_channel_operation_result {
 	AUX_CHANNEL_OPERATION_SUCCEEDED,
 	AUX_CHANNEL_OPERATION_FAILED_REASON_UNKNOWN,
 	AUX_CHANNEL_OPERATION_FAILED_INVALID_REPLY,
-	AUX_CHANNEL_OPERATION_FAILED_TIMEOUT
+	AUX_CHANNEL_OPERATION_FAILED_TIMEOUT,
+	AUX_CHANNEL_OPERATION_FAILED_HPD_DISCON
 };
 
 struct aux_engine;

drivers/gpu/drm/amd/display/dc/i2caux/dce110/aux_engine_dce110.c

@@ -291,6 +291,12 @@ static void process_channel_reply(
 	value = REG_GET(AUX_SW_STATUS,
 			AUX_SW_REPLY_BYTE_COUNT, &bytes_replied);
 
+	/* in case HPD is LOW, exit AUX transaction */
+	if ((value & AUX_SW_STATUS__AUX_SW_HPD_DISCON_MASK)) {
+		reply->status = AUX_TRANSACTION_REPLY_HPD_DISCON;
+		return;
+	}
+
 	if (bytes_replied) {
 		uint32_t reply_result;
 
@@ -347,8 +353,10 @@ static void process_channel_reply(
 		 * because there was surely an error that was asserted
 		 * that should have been handled
 		 * for hot plug case, this could happens*/
-		if (!(value & AUX_SW_STATUS__AUX_SW_HPD_DISCON_MASK))
+		if (!(value & AUX_SW_STATUS__AUX_SW_HPD_DISCON_MASK)) {
+			reply->status = AUX_TRANSACTION_REPLY_INVALID;
 			ASSERT_CRITICAL(false);
+		}
 	}
 }
 
@@ -371,6 +379,10 @@ static enum aux_channel_operation_result get_channel_status(
 	value = REG_WAIT(AUX_SW_STATUS, AUX_SW_DONE, 1,
 				10, aux110->timeout_period/10);
 
+	/* in case HPD is LOW, exit AUX transaction */
+	if ((value & AUX_SW_STATUS__AUX_SW_HPD_DISCON_MASK))
+		return AUX_CHANNEL_OPERATION_FAILED_HPD_DISCON;
+
 	/* Note that the following bits are set in 'status.bits'
 	 * during CTS 4.2.1.2 (FW 3.3.1):
 	 * AUX_SW_RX_MIN_COUNT_VIOL, AUX_SW_RX_INVALID_STOP,
@@ -402,10 +414,10 @@ static enum aux_channel_operation_result get_channel_status(
 			return AUX_CHANNEL_OPERATION_SUCCEEDED;
 		}
 	} else {
-		/*time_elapsed >= aux_engine->timeout_period */
-		if (!(value & AUX_SW_STATUS__AUX_SW_HPD_DISCON_MASK))
-			ASSERT_CRITICAL(false);
-
+		/*time_elapsed >= aux_engine->timeout_period
+		 *  AUX_SW_STATUS__AUX_SW_HPD_DISCON = at this point
+		 */
+		ASSERT_CRITICAL(false);
 		return AUX_CHANNEL_OPERATION_FAILED_TIMEOUT;
 	}
 }

drivers/gpu/drm/amd/display/dc/i2caux/engine.h

@@ -53,7 +53,8 @@ enum i2caux_transaction_status {
 	I2CAUX_TRANSACTION_STATUS_FAILED_INCOMPLETE,
 	I2CAUX_TRANSACTION_STATUS_FAILED_OPERATION,
 	I2CAUX_TRANSACTION_STATUS_FAILED_INVALID_OPERATION,
-	I2CAUX_TRANSACTION_STATUS_FAILED_BUFFER_OVERFLOW
+	I2CAUX_TRANSACTION_STATUS_FAILED_BUFFER_OVERFLOW,
+	I2CAUX_TRANSACTION_STATUS_FAILED_HPD_DISCON
 };
 
 struct i2caux_transaction_request {

drivers/gpu/drm/amd/display/include/ddc_service_types.h

@@ -40,7 +40,8 @@ enum ddc_result {
 	DDC_RESULT_FAILED_INCOMPLETE,
 	DDC_RESULT_FAILED_OPERATION,
 	DDC_RESULT_FAILED_INVALID_OPERATION,
-	DDC_RESULT_FAILED_BUFFER_OVERFLOW
+	DDC_RESULT_FAILED_BUFFER_OVERFLOW,
+	DDC_RESULT_FAILED_HPD_DISCON
 };
 
 enum ddc_service_type {