Re: [alsa-devel] [PATCH 2/5] ALSA: snd-usb: switch over to new endpoint streaming logic

On 10/31/2011 01:10 PM, Daniel Mack wrote:

@@ -276,6 +312,15 @@ static int set_format(struct snd_usb_substream *subs, struct audioformat *fmt) if (((is_playback && attr == USB_ENDPOINT_SYNC_ASYNC) || (! is_playback && attr == USB_ENDPOINT_SYNC_ADAPTIVE)) && altsd->bNumEndpoints >= 2) {

• switch (subs->stream->chip->usb_id) {
  

• case USB_ID(0x0763, 0x2080): /* M-Audio FastTrack Ultra */
  

• case USB_ID(0x0763, 0x2081):
  

• 	ep = 0x81;
  

• 	iface = usb_ifnum_to_if(dev, 2);
  

• 	alts = &iface->altsetting[1];
  

Better check that the device actually has these descriptors.

+int snd_usb_substream_capture_trigger(struct snd_pcm_substream *substream, int cmd) +{

• case SNDRV_PCM_TRIGGER_START:

• err = start_endpoints(subs);
  

The trigger callback should execute very quickly; the initial URB submission should be handled in the prepare callback.

Regards, Clemens