This is a note to let you know that I've just added the patch titled drm/msm/dsi: set default num_data_lanes to the 5.15-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-msm-dsi-set-default-num_data_lanes.patch and it can be found in the queue-5.15 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let <stable@xxxxxxxxxxxxxxx> know about it. commit b1d5ea1692b18dccd01e3899f776b8d31f34d115 Author: Philip Chen <philipchen@xxxxxxxxxxxx> Date: Sat Oct 30 10:08:50 2021 -0700 drm/msm/dsi: set default num_data_lanes [ Upstream commit cd92cc187c053ab010a1570e2d61d68394a5c725 ] If "data_lanes" property of the dsi output endpoint is missing in the DT, num_data_lanes would be 0 by default, which could cause dsi_host_attach() to fail if dsi->lanes is set to a non-zero value by the bridge driver. According to the binding document of msm dsi controller, the input/output endpoint of the controller is expected to have 4 lanes. So let's set num_data_lanes to 4 by default. Signed-off-by: Philip Chen <philipchen@xxxxxxxxxxxx> Reviewed-by: Douglas Anderson <dianders@xxxxxxxxxxxx> Reviewed-by: Stephen Boyd <swboyd@xxxxxxxxxxxx> Link: https://lore.kernel.org/r/20211030100812.1.I6cd9af36b723fed277d34539d3b2ba4ca233ad2d@changeid Signed-off-by: Rob Clark <robdclark@xxxxxxxxxxxx> Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx> diff --git a/drivers/gpu/drm/msm/dsi/dsi_host.c b/drivers/gpu/drm/msm/dsi/dsi_host.c index ea641151e77e7..dc85974c78975 100644 --- a/drivers/gpu/drm/msm/dsi/dsi_host.c +++ b/drivers/gpu/drm/msm/dsi/dsi_host.c @@ -1696,6 +1696,8 @@ static int dsi_host_parse_lane_data(struct msm_dsi_host *msm_host, if (!prop) { DRM_DEV_DEBUG(dev, "failed to find data lane mapping, using default\n"); + /* Set the number of date lanes to 4 by default. */ + msm_host->num_data_lanes = 4; return 0; }