On Tuesday, February 28th, 2023 at 13:31, Peter Stuge <peter@xxxxxxxx> wrote: > > Would it be possible to set the PATH connector property based on the > > USB port used by gud? > > Sadly not really easily. > > The physical topology underneath each host controller is stable but > bus numbers (usb1, usb2 etc.) are not. Oh, that's news to me. So if I unplug and replug a USB device, the bus number and bus device number might change? Or does this happen after a power-cycle? Or is this hardware-specific? The guarantee we need for PATH is that the exact same hardware configuration will always retain the same PATH. > For onboard host controllers it could be possible to anchor to a > PCI or platform bus device. But the PCI bus device isn't enough I think? If I have a onboard host controller with 2 physical USB ports, the PCI bus device isn't enough to tell these 2 physical ports apart? > But busses on expansion cards can't be recognized so easily without > using maybe serial numbers - which may be cloned across multiple > devices - we can't know. > > > 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. > > How about using e.g. the serial number of the gud USB device instead > of host topology, or maybe some other information from the panel > behind it? The PATH property is really about the port path, not the sink. IOW, if I have two USB displays, one USB port, and switch between the two displays on this one port, the PATH property isn't supposed to change.
