gud: set PATH connector property

[Noralf Trønnes]

Hi Simon,

On 2/28/23 12:36, Simon Ser wrote:
> Hi Noralf,
> 
> Would it be possible to set the PATH connector property based on the
> USB port used by gud?
> 
> This would give user-space a persistent identifier for the connector:
> if the user plugs in a USB display on a given port, the PATH would be
> the same even if the machine rebooted or the displays were plugged in
> in a different order.
> 
> DP-MST already sets this. User-space can use this property to store
> output configuration metadata.
> 

drm_mode_connector_set_path_property() docs:

This creates a property to expose to userspace to specify a connector
path. This is mainly used for DisplayPort MST where connectors have a
topology and we want to allow userspace to give them more meaningful names.

Here it says that it's about giving meaningful names to connectors, I
think it would be useful to know that a HDMI-A connector is on a USB
adapter for instance and not on the laptop/motherboard.

You mention output configuration however, why does userspace use the
path to a connector when storing the multi display config and not some
unique property on the displays themselves like the serial number?

Noralf.