drm/mediatek: dp: Change the aux retries times when receiving AUX_DEFER

DP 1.4a Section 2.8.7.1.5.6.1:
A DP Source device shall retry at least seven times upon receiving
AUX_DEFER before giving up the AUX transaction.

The drm_dp_i2c_do_msg() function in the drm_dp_helper.c file will
judge the status of the msg->reply parameter passed to aux_transfer
for different processing.

Fixes: f70ac09 ("drm/mediatek: Add MT8195 Embedded DisplayPort driver")
Signed-off-by: Xinlei Lee <[email protected]>
Link: https://patchwork.kernel.org/project/linux-mediatek/patch/[email protected]/
Signed-off-by: Chun-Kuang Hu <[email protected]>

Author: panghu-xinlei

drivers/gpu/drm/mediatek/mtk_dp.c

@@ -806,10 +806,9 @@ static int mtk_dp_aux_wait_for_completion(struct mtk_dp *mtk_dp, bool is_read)
 }
 
 static int mtk_dp_aux_do_transfer(struct mtk_dp *mtk_dp, bool is_read, u8 cmd,
-				  u32 addr, u8 *buf, size_t length)
+				  u32 addr, u8 *buf, size_t length, u8 *reply_cmd)
 {
 	int ret;
-	u32 reply_cmd;
 
 	if (is_read && (length > DP_AUX_MAX_PAYLOAD_BYTES ||
 			(cmd == DP_AUX_NATIVE_READ && !length)))
@@ -841,10 +840,10 @@ static int mtk_dp_aux_do_transfer(struct mtk_dp *mtk_dp, bool is_read, u8 cmd,
 	/* Wait for feedback from sink device. */
 	ret = mtk_dp_aux_wait_for_completion(mtk_dp, is_read);
 
-	reply_cmd = mtk_dp_read(mtk_dp, MTK_DP_AUX_P0_3624) &
-		    AUX_RX_REPLY_COMMAND_AUX_TX_P0_MASK;
+	*reply_cmd = mtk_dp_read(mtk_dp, MTK_DP_AUX_P0_3624) &
+		     AUX_RX_REPLY_COMMAND_AUX_TX_P0_MASK;
 
-	if (ret || reply_cmd) {
+	if (ret) {
 		u32 phy_status = mtk_dp_read(mtk_dp, MTK_DP_AUX_P0_3628) &
 				 AUX_RX_PHY_STATE_AUX_TX_P0_MASK;
 		if (phy_status != AUX_RX_PHY_STATE_AUX_TX_P0_RX_IDLE) {
@@ -2071,7 +2070,7 @@ static ssize_t mtk_dp_aux_transfer(struct drm_dp_aux *mtk_aux,
 		ret = mtk_dp_aux_do_transfer(mtk_dp, is_read, request,
 					     msg->address + accessed_bytes,
 					     msg->buffer + accessed_bytes,
-					     to_access);
+					     to_access, &msg->reply);
 
 		if (ret) {
 			drm_info(mtk_dp->drm_dev,
@@ -2081,7 +2080,6 @@ static ssize_t mtk_dp_aux_transfer(struct drm_dp_aux *mtk_aux,
 		accessed_bytes += to_access;
 	} while (accessed_bytes < msg->size);
 
-	msg->reply = DP_AUX_NATIVE_REPLY_ACK | DP_AUX_I2C_REPLY_ACK;
 	return msg->size;
 err:
 	msg->reply = DP_AUX_NATIVE_REPLY_NACK | DP_AUX_I2C_REPLY_NACK;