From: Wojciech Macek <wmacek@chromium.org> stable inclusion from stable-v6.6.33 commit 22432baba48a4d07a2775a029532c8aac4b5df26 category: bugfix bugzilla: https://gitee.com/openeuler/kernel/issues/IAD6H2 Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=... -------------------------------- [ 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@chromium.org> Reviewed-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com> Reviewed-by: CK Hu <ck.hu@mediatek.com> Link: https://patchwork.kernel.org/project/dri-devel/patch/20240417103819.990512-1... Signed-off-by: Chun-Kuang Hu <chunkuang.hu@kernel.org> Signed-off-by: Sasha Levin <sashal@kernel.org> Signed-off-by: Wang Hai <wanghai38@huawei.com> --- drivers/gpu/drm/mediatek/mtk_dp.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/drivers/gpu/drm/mediatek/mtk_dp.c b/drivers/gpu/drm/mediatek/mtk_dp.c index 4052a3133b57..af03a22772fe 100644 --- a/drivers/gpu/drm/mediatek/mtk_dp.c +++ b/drivers/gpu/drm/mediatek/mtk_dp.c @@ -2080,7 +2080,7 @@ 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; } -- 2.17.1