This is a note to let you know that I've just added the patch titled
drm/mediatek: dp: Fix mtk_dp_aux_transfer return value
to the 6.9-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
drm-mediatek-dp-fix-mtk_dp_aux_transfer-return-value.patch
and it can be found in the queue-6.9 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit a6aaf4078c2e9cb21372e92ae2435ef7e68a0068
Author: Wojciech Macek <wmacek@xxxxxxxxxxxx>
Date: Wed Apr 17 10:38:19 2024 +0000
drm/mediatek: dp: Fix mtk_dp_aux_transfer return value
[ Upstream commit 8431fff9e0f3fc1c5844cf99a73b49b63ceed481 ]
In case there is no DP device attached to the port the
transfer function should return IO error, similar to what
other drivers do.
In case EAGAIN is returned then any read from /dev/drm_dp_aux
device ends up in an infinite loop as the upper layers
constantly repeats the transfer request.
Fixes: f70ac097a2cf ("drm/mediatek: Add MT8195 Embedded DisplayPort driver")
Signed-off-by: Wojciech Macek <wmacek@xxxxxxxxxxxx>
Reviewed-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@xxxxxxxxxxxxx>
Reviewed-by: CK Hu <ck.hu@xxxxxxxxxxxx>
Link: https://patchwork.kernel.org/project/dri-devel/patch/20240417103819.990512-1-wmacek@xxxxxxxxxxxx/
Signed-off-by: Chun-Kuang Hu <chunkuang.hu@xxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/drivers/gpu/drm/mediatek/mtk_dp.c b/drivers/gpu/drm/mediatek/mtk_dp.c
index 0ba72102636aa..536366956447a 100644
--- a/drivers/gpu/drm/mediatek/mtk_dp.c
+++ b/drivers/gpu/drm/mediatek/mtk_dp.c
@@ -2104,7 +2104,7 @@ static ssize_t mtk_dp_aux_transfer(struct drm_dp_aux *mtk_aux,
if (mtk_dp->bridge.type != DRM_MODE_CONNECTOR_eDP &&
!mtk_dp->train_info.cable_plugged_in) {
- ret = -EAGAIN;
+ ret = -EIO;
goto err;
}
