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sound: usb-audio: use normal number of frames for no-data URBs

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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: Clemens Ladisch <clemens@ladisch.de>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
This commit is contained in:
Clemens Ladisch 2009-01-26 08:08:34 +01:00 committed by Takashi Iwai
parent 8693290b90
commit b7eb4a06e9
1 changed files with 3 additions and 3 deletions
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6
sound/usb/usbaudio.c
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@ -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,