Hi, Xinlei:
<xinlei.lee@xxxxxxxxxxxx> 於 2023年3月29日 週三 下午2:43寫道：
>
> From: Xinlei Lee <xinlei.lee@xxxxxxxxxxxx>
>
> 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@xxxxxxxxxxxx>
> ---
> 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;
In your description, you just mention the retry count is 7 times, but
you does not mention you should change the reply. Why you modify this?
And where is the 7 times retry?
Regards,
Chun-Kuang.
> return msg->size;
> err:
> msg->reply = DP_AUX_NATIVE_REPLY_NACK | DP_AUX_I2C_REPLY_NACK;
> --
> 2.18.0
>
