[ 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: f70ac097a2 ("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-wmacek@chromium.org/
Signed-off-by: Chun-Kuang Hu <chunkuang.hu@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
22432baba4