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Commit b7eb4a06 authored by Clemens Ladisch's avatar Clemens Ladisch Committed by Takashi Iwai
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sound: usb-audio: use normal number of frames for no-data URBs 



When sending a silence URB (before playback has started, or when it is
paused), use the number of frames that would be normally sent instead of
a single frame so that the rate at which completion interrupts arrive is
consistent.

Signed-off-by: default avatarClemens Ladisch <clemens@ladisch.de>
Signed-off-by: default avatarTakashi Iwai <tiwai@suse.de>
parent 8693290b

sound/usb/usbaudio.c

+3 −3
Original line number Diff line number Diff line
@@ -525,7 +525,7 @@ static int snd_usb_audio_next_packet_size(struct snd_usb_substream *subs) 
/*

 * Prepare urb for streaming before playback starts or when paused.

 *

 * We don't have any data, so we send a frame of silence.

 * We don't have any data, so we send silence.

 */

static int prepare_nodata_playback_urb(struct snd_usb_substream *subs,

				       struct snd_pcm_runtime *runtime,
@@ -537,13 +537,13 @@ static int prepare_nodata_playback_urb(struct snd_usb_substream *subs, 


	offs = 0;

	urb->dev = ctx->subs->dev;

	urb->number_of_packets = subs->packs_per_ms;

	for (i = 0; i < subs->packs_per_ms; ++i) {

	for (i = 0; i < ctx->packets; ++i) {

		counts = snd_usb_audio_next_packet_size(subs);

		urb->iso_frame_desc[i].offset = offs * stride;

		urb->iso_frame_desc[i].length = counts * stride;

		offs += counts;

	}

	urb->number_of_packets = ctx->packets;

	urb->transfer_buffer_length = offs * stride;

	memset(urb->transfer_buffer,

	       subs->cur_audiofmt->format == SNDRV_PCM_FORMAT_U8 ? 0x80 : 0,