1 files changed, 31 insertions, 9 deletions

diff --git a/drivers/gpu/drm/radeon/atombios_dp.c b/drivers/gpu/drm/radeon/atombios_dp.c
index 645b84b..79e8ebc 100644
--- a/drivers/gpu/drm/radeon/atombios_dp.c
+++ b/drivers/gpu/drm/radeon/atombios_dp.c
@@ -115,6 +115,7 @@ static int radeon_dp_aux_native_write(struct radeon_connector *radeon_connector,
 	u8 msg[20];
 	int msg_bytes = send_bytes + 4;
 	u8 ack;
+	unsigned retry;
 
 	if (send_bytes > 16)
 		return -1;
@@ -125,20 +126,22 @@ static int radeon_dp_aux_native_write(struct radeon_connector *radeon_connector,
 	msg[3] = (msg_bytes << 4) | (send_bytes - 1);
 	memcpy(&msg[4], send, send_bytes);
 
-	while (1) {
+	for (retry = 0; retry < 4; retry++) {
 		ret = radeon_process_aux_ch(dig_connector->dp_i2c_bus,
 					    msg, msg_bytes, NULL, 0, delay, &ack);
-		if (ret < 0)
+		if (ret == -EBUSY)
+			continue;
+		else if (ret < 0)
 			return ret;
 		if ((ack & AUX_NATIVE_REPLY_MASK) == AUX_NATIVE_REPLY_ACK)
-			break;
+			return send_bytes;
 		else if ((ack & AUX_NATIVE_REPLY_MASK) == AUX_NATIVE_REPLY_DEFER)
 			udelay(400);
 		else
 			return -EIO;
 	}
 
-	return send_bytes;
+	return -EIO;
 }
 
 static int radeon_dp_aux_native_read(struct radeon_connector *radeon_connector,
@@ -149,26 +152,31 @@ static int radeon_dp_aux_native_read(struct radeon_connector *radeon_connector,
 	int msg_bytes = 4;
 	u8 ack;
 	int ret;
+	unsigned retry;
 
 	msg[0] = address;
 	msg[1] = address >> 8;
 	msg[2] = AUX_NATIVE_READ << 4;
 	msg[3] = (msg_bytes << 4) | (recv_bytes - 1);
 
-	while (1) {
+	for (retry = 0; retry < 4; retry++) {
 		ret = radeon_process_aux_ch(dig_connector->dp_i2c_bus,
 					    msg, msg_bytes, recv, recv_bytes, delay, &ack);
-		if (ret == 0)
-			return -EPROTO;
-		if (ret < 0)
+		if (ret == -EBUSY)
+			continue;
+		else if (ret < 0)
 			return ret;
 		if ((ack & AUX_NATIVE_REPLY_MASK) == AUX_NATIVE_REPLY_ACK)
 			return ret;
 		else if ((ack & AUX_NATIVE_REPLY_MASK) == AUX_NATIVE_REPLY_DEFER)
 			udelay(400);
+		else if (ret == 0)
+			return -EPROTO;
 		else
 			return -EIO;
 	}
+
+	return -EIO;
 }
 
 static void radeon_write_dpcd_reg(struct radeon_connector *radeon_connector,
@@ -232,7 +240,9 @@ int radeon_dp_i2c_aux_ch(struct i2c_adapter *adapter, int mode,
 	for (retry = 0; retry < 4; retry++) {
 		ret = radeon_process_aux_ch(auxch,
 					    msg, msg_bytes, reply, reply_bytes, 0, &ack);
-		if (ret < 0) {
+		if (ret == -EBUSY)
+			continue;
+		else if (ret < 0) {
 			DRM_DEBUG_KMS("aux_ch failed %d\n", ret);
 			return ret;
 		}
@@ -613,6 +623,18 @@ static bool radeon_dp_get_link_status(struct radeon_connector *radeon_connector,
 	return true;
 }
 
+bool radeon_dp_needs_link_train(struct radeon_connector *radeon_connector)
+{
+	u8 link_status[DP_LINK_STATUS_SIZE];
+	struct radeon_connector_atom_dig *dig = radeon_connector->con_priv;
+
+	if (!radeon_dp_get_link_status(radeon_connector, link_status))
+		return false;
+	if (dp_channel_eq_ok(link_status, dig->dp_lane_count))
+		return false;
+	return true;
+}
+
 struct radeon_dp_link_train_info {
 	struct radeon_device *rdev;
 	struct drm_encoder *encoder;