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From:   <xinlei.lee@mediatek.com>
To:     <chunkuang.hu@kernel.org>, <p.zabel@pengutronix.de>,
        <airlied@linux.ie>, <daniel@ffwll.ch>, <matthias.bgg@gmail.com>
CC:     <dri-devel@lists.freedesktop.org>,
        <linux-mediatek@lists.infradead.org>,
        <linux-arm-kernel@lists.infradead.org>,
        <linux-kernel@vger.kernel.org>,
        <Project_Global_Chrome_Upstream_Group@mediatek.com>,
        Xinlei Lee <xinlei.lee@mediatek.com>
Subject: [PATCH] drm/mediatek: dp: change the aux retries times when receiving AUX_DEFER
Date:   Wed, 29 Mar 2023 14:43:23 +0800
Message-ID: <1680072203-10394-1-git-send-email-xinlei.lee@mediatek.com>
MIME-Version: 1.0
Content-Type: text/plain
Precedence: bulk

From: Xinlei Lee <xinlei.lee@mediatek.com>

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
ange-the-aux-retries-times-when-re.patchfor different processing.

Fixes: f70ac097a2cf ("drm/mediatek: Add MT8195 Embedded DisplayPort driver")
Signed-off-by: Xinlei Lee <xinlei.lee@mediatek.com>
---
 drivers/gpu/drm/mediatek/mtk_dp.c | 12 +++++-------
 1 file changed, 5 insertions(+), 7 deletions(-)

diff --git a/drivers/gpu/drm/mediatek/mtk_dp.c b/drivers/gpu/drm/mediatek/mtk_dp.c
index 1f94fcc144d3..767b71da31a4 100644
--- a/drivers/gpu/drm/mediatek/mtk_dp.c
+++ b/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) {
@@ -2070,7 +2069,7 @@ 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,
@@ -2080,7 +2079,6 @@ 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;
-- 
2.18.0