On Tue, 2023-01-17 at 17:14 +0100, Greg Kroah-Hartman wrote: > On Tue, Jan 17, 2023 at 04:17:23PM +0100, Bastien Nocera wrote: > > Hey, > > > > TLDR: new sysfs attribute that makes it possible to leave receivers > > for > > wireless headsets plugged in. At the USB level, or at the base > > driver > > level? > > > > Longer version: > > I started working on implementing support for some wireless > > headsets > > that use USB receivers to communicate to the headset itself. > > Would this also include wireless keyboard/mice recievers? This could also be used by certain keyboard or mice receivers, if the keyboard or mouse is kept constantly connected and there's a way to find out whether it's connected or not. > Why is "wireless" somehow a special attribute that userspace needs to > know about? "wireless" isn't the attribute user-space would be interested in, "wireless status" would be. If the headset's wireless status is "disconnected", then the headset is unavailable. Then user-space can route the audio accordingly. > > The USB receivers have multiple interfaces, and independent drivers > > for > > each, as is wont to do for USB devices. There's usually a HID > > interface > > to do the custom stuff (LEDs, battery status, connection status, > > etc.) > > and a standard audio class interface. > > This probably should be an interface attribute (as Alan points out), > as > it's not a device attribute (think about updating the firmware for > one > of these, that's on an interface for the reciever you plugged in, not > on > the other end of the wireless connection...) OK, fair enough. > > Those drivers don't know anything about each other, and getting > > them to > > talk to each other would be rather complicated. Additionally the > > audio > > interface is still somewhat functional when the headset is > > disconnected. > > Those drivers shouldn't know about each other, that's up to userspace > to > group and control if needed. No kernel interactions should be > needed. > > > In the end, I came up with this new sysfs attribute that would make > > it > > possible for user-space (PulseAudio or Pipewire) to know whether > > the > > receiver is plugged in or not. > > Again, should be an interface attribute, if at all. > > > That allows user-space to not show the battery information for the > > device (rather than 0 percent), not offer the headset as an output, > > and > > potentially automatically switch to it when the headset is powered > > on. > > Same for a keyboard/mouse, right? Yes, although I haven't found devices where this would be useful. I'll reimplement this as an interface attribute. Thanks very much to you and Alan for the quick replies. Cheers
