On Wed, 21 Nov 2007, Clemens Ladisch wrote: > Takashi Iwai wrote: > > Yes, querying channel mapping is another missing piece with popular > > demand. > > > > The implementation would be easy, I guess. But we have to define the > > way to inform this from kernel to user space: whether create a new > > ioctl or extend the existing ones (if possible)... > > It's just metadata that describes a PCM device, so I think we should use > TLV for this. > > The existing struct snd_ctl_tlv uses a single integer to identify > control elements. We could restrict control numid's to 31 bits and > use the upper bit to signal that this value includes device type and > device number in the lower bits, if we want to reuse the same TLV > ioctls. We can also encode PCM device / subdevice numbers to data structure. But I think that best way is to extend channel_info PCM ioctl (create new version and emulate old one - it should be quite easy to implement). Jaroslav ----- Jaroslav Kysela <perex@xxxxxxxx> Linux Kernel Sound Maintainer ALSA Project _______________________________________________ Alsa-devel mailing list Alsa-devel@xxxxxxxxxxxxxxxx http://mailman.alsa-project.org/mailman/listinfo/alsa-devel
