Cameron Stone wrote: > I'm writing some firmware for a USB microphone array with multiple > configurations, and I'm wondering if it's possible to tell ALSA which > configuration to use in a module option or something (device_setup, > perhaps). > > I've been looking through usbaudio.c in the kernel source > (2.6.28-11-generic from the ubuntu Jaunty package), and I can't find any > generic device configuration like that. > > If this is not possible, does anyone have any recommendations on how to > implement this? I can imagine doing it using quirks for this particular > USB_ID, but this seems like a fairly generic type of capability, so I'd > like to make it general if possible. While the USB specifications define configurations, there is no generic way how a driver could automatically determine which configuration to use. > If anyone is wondering *why* I want multiple configurations: it's for > bandwidth management. I have 8 channels, but I want to be able to sample > 1 channel as fast as possible without wasting bandwidth on the other 7. > I couldn't figure out a way to do that with a single configurations. Bandwidth management is implemented by having multiple alternate settings for the audio streaming interface. (This is why alternate setting zero must have no endpoint or a zero-sized endpoint, so that in the default case, the interface does not use any bandwidth.) Best regards, Clemens _______________________________________________ Alsa-devel mailing list Alsa-devel@xxxxxxxxxxxxxxxx http://mailman.alsa-project.org/mailman/listinfo/alsa-devel
