Re: [alsa-devel] [PATCH 1/5] ALSA: snd-usb: implement new endpoint streaming model

Daniel Mack wrote:

+void snd_usb_handle_sync_urb(struct snd_usb_endpoint *ep, +{

• if (snd_usb_endpoint_implict_feedback_sink(ep) && ep->use_count > 0) { ...

• for (i = 0; i < ep->nurbs; i++)
  

• 	if (!test_and_set_bit(i, &ep->active_mask)) {
  

• 		out_urb = ep->urb[i].urb;
  

• 		break;
  

• 	}
  

• if (!out_urb) {
  

• 	snd_printk(KERN_ERR "Unable to find an urb for playback (nurbs %d)\n",
  

• 		   ep->nurbs);
  

AFAICS the driver tries for all URBS to be queued at all times. So if the HC driver completes a sync URB before the corresponding playback URB, it may be possible for this error to happen.

Regards, Clemens