From: Simon Ser Date: Mon, 23 Oct 2023 20:36:39 +0000 (+0000) Subject: drm/doc: describe PATH format for DP MST X-Git-Url: http://git.maquefel.me/?a=commitdiff_plain;h=88b02ebca8b6ea7457bed6809b1dd575420b7544;p=linux.git drm/doc: describe PATH format for DP MST This is already uAPI, xserver parses it. It's useful to document since user-space might want to lookup the parent connector. Additionally, people (me included) have misunderstood the PATH property for being stable across reboots, but since a KMS object ID is baked in there that's not the case. So PATH shouldn't be used as-is in config files and such. Signed-off-by: Simon Ser Reviewed-by: Dmitry Baryshkov Acked-by: Pekka Paalanen Cc: Daniel Vetter Link: https://patchwork.freedesktop.org/patch/msgid/20231023203629.198109-1-contact@emersion.fr --- diff --git a/drivers/gpu/drm/drm_connector.c b/drivers/gpu/drm/drm_connector.c index c3725086f4132..b0516505f7ae9 100644 --- a/drivers/gpu/drm/drm_connector.c +++ b/drivers/gpu/drm/drm_connector.c @@ -1198,6 +1198,12 @@ static const u32 dp_colorspaces = * drm_connector_set_path_property(), in the case of DP MST with the * path property the MST manager created. Userspace cannot change this * property. + * + * In the case of DP MST, the property has the format + * ``mst:-`` where ```` is the KMS object ID of the + * parent connector and ```` is a hyphen-separated list of DP MST + * port numbers. Note, KMS object IDs are not guaranteed to be stable + * across reboots. * TILE: * Connector tile group property to indicate how a set of DRM connector * compose together into one logical screen. This is used by both high-res