Commit 9624ea81 authored by Clemens Ladisch's avatar Clemens Ladisch Committed by Jaroslav Kysela
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[ALSA] usb-audio: actually schedule playback URBs at frame boundaries 



USB generic driver
Change prepare_playback_urb() not to stop preparing packets before a
frame boundary has been reached.

Signed-off-by: default avatarClemens Ladisch <clemens@ladisch.de>
parent 7efd8bc8

sound/usb/usbaudio.c

+7 −1
Original line number Diff line number Diff line
@@ -164,6 +164,7 @@ struct snd_usb_substream { 
	unsigned int curframesize;	/* current packet size in frames (for capture) */

	unsigned int fill_max: 1;	/* fill max packet size always */

	unsigned int fmt_type;		/* USB audio format type (1-3) */

	unsigned int packs_per_ms;	/* packets per millisecond (for playback) */



	unsigned int running: 1;	/* running status */
@@ -537,10 +538,14 @@ static int prepare_playback_urb(snd_usb_substream_t *subs, 
					urb->iso_frame_desc[i].length = 0;

					urb->number_of_packets++;

				}

			}

				break;

			}

 		}

		/* finish at the frame boundary at/after the period boundary */

		if (period_elapsed &&

		    (i & (subs->packs_per_ms - 1)) == subs->packs_per_ms - 1)

			break;

	}

	if (subs->hwptr_done + offs > runtime->buffer_size) {

		/* err, the transferred area goes over buffer boundary. */

		unsigned int len = runtime->buffer_size - subs->hwptr_done;
@@ -907,6 +912,7 @@ static int init_substream_urbs(snd_usb_substream_t *subs, unsigned int period_by 
		packs_per_ms = 8 >> subs->datainterval;

	else

		packs_per_ms = 1;

	subs->packs_per_ms = packs_per_ms;



	if (is_playback) {

		urb_packs = nrpacks;