[PATCH v15 07/11] drm/mediatek: Add retry to prevent misjudgment for sink devices
From: Bo-Chen Chen <hidden>
Date: 2022-07-27 04:51:27
Also in:
dri-devel, linux-arm-kernel, linux-devicetree, linux-mediatek, lkml
Subsystem:
drm drivers, drm drivers for mediatek, the rest · Maintainers:
David Airlie, Simona Vetter, Chun-Kuang Hu, Philipp Zabel, Linus Torvalds
For some DP dungles, we need to train more than onece to confirm that we don't misjudge the status of sink device. Signed-off-by: Bo-Chen Chen <redacted> --- drivers/gpu/drm/mediatek/mtk_dp.c | 21 ++++++++++++++++++--- 1 file changed, 18 insertions(+), 3 deletions(-)
diff --git a/drivers/gpu/drm/mediatek/mtk_dp.c b/drivers/gpu/drm/mediatek/mtk_dp.c
index ce817cb59445..80d7d6488105 100644
--- a/drivers/gpu/drm/mediatek/mtk_dp.c
+++ b/drivers/gpu/drm/mediatek/mtk_dp.c@@ -42,6 +42,7 @@ #define MTK_DP_CHECK_SINK_CAP_TIMEOUT_COUNT 3 #define MTK_DP_TBC_BUF_READ_START_ADDR 0x08 #define MTK_DP_TRAIN_DOWNSCALE_RETRY 8 +#define MTK_DP_TRAIN_CLEAR_RETRY 50 struct mtk_dp_train_info { bool tps3;
@@ -1431,11 +1432,25 @@ static int mtk_dp_video_config(struct mtk_dp *mtk_dp) static int mtk_dp_training(struct mtk_dp *mtk_dp) { + short max_retry = MTK_DP_TRAIN_CLEAR_RETRY; int ret; - ret = mtk_dp_train_start(mtk_dp); - if (ret) - return ret; + /* + * We do retry to confirm that we don't misjudge the sink status. + * If it is still failed, we can confirm there are some issues for the + * sink device. + */ + do { + ret = mtk_dp_train_start(mtk_dp); + if (!ret) + break; + } while (--max_retry); + + dev_info(mtk_dp->dev, "dp training clear retry times: %d\n", + MTK_DP_TRAIN_CLEAR_RETRY - max_retry); + + if (!max_retry) + return -ETIMEDOUT; ret = mtk_dp_video_config(mtk_dp); if (ret)
--
2.18.0