ALSA: usb-audio: Add keep_iface flag
Introduce a new flag to struct snd_usb_audio for allowing the device
to skip usb_set_interface() calls at changing or closing the stream.
As of this patch, the flag is nowhere set, so it's just a place
holder. The dynamic switching will be added in the following patch.
A background information for this change:
Dell WD15 dock with Realtek chip gives a very long pause at each time
the driver changes the altset, which eventually happens at every PCM
stream open/close and parameter change. As the long pause happens in
each usb_set_interface() call, there is nothing we can do as long as
it's called. The workaround is to reduce calling it as much as
possible, and this flag indicates that behavior.
Signed-off-by: Takashi Iwai <tiwai@suse.de>
2 files changed