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sound: usb-audio: do not make URBs longer than sync packet interval 

Using more packets in one URB do avoid interrupts does not make sense
when we have a sync pipe whose packets generate interrupts more often.
Therefore, limit the URB size to the synchronization packet interval.

Signed-off-by: Clemens Ladisch <clemens@ladisch.de>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
This commit is contained in:
Clemens Ladisch 2009-08-10 10:07:35 +02:00 committed by Takashi Iwai
parent a65dd997b3
commit 765e8db078
1 changed files with 2 additions and 0 deletions
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2
sound/usb/usbaudio.c
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@ -1083,6 +1083,8 @@ static int init_substream_urbs(struct snd_usb_substream *subs, unsigned int peri
} else
urb_packs = 1;
urb_packs *= packs_per_ms;
if (subs->syncpipe)
urb_packs = min(urb_packs, 1 << subs->syncinterval);
/* decide how many packets to be used */
if (is_playback) {