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[ALSA] usb-audio - use proper interval between synchronization packets 

USB generic driver
Add sanity checks when reading the bRefresh value, and actually use it
for the synchronization packets instead of polling at 1000 Hz.

Signed-off-by: Clemens Ladisch <clemens@ladisch.de>
This commit is contained in:
Clemens Ladisch 2005-05-02 08:53:46 +02:00 committed by Jaroslav Kysela
parent 4dc40a3cc4
commit 1149a64fe4
1 changed files with 7 additions and 5 deletions
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12
sound/usb/usbaudio.c
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@ -1051,10 +1051,7 @@ static int init_substream_urbs(snd_usb_substream_t *subs, unsigned int period_by
u->urb->pipe = subs->syncpipe;
u->urb->transfer_flags = URB_ISO_ASAP;
u->urb->number_of_packets = u->packets;
if (snd_usb_get_speed(subs->dev) == USB_SPEED_HIGH)
u->urb->interval = 8;
else
u->urb->interval = 1;
u->urb->interval = 1 << subs->syncinterval;
u->urb->context = u;
u->urb->complete = snd_usb_complete_callback(snd_complete_sync_urb);
}
@ -1272,7 +1269,12 @@ static int set_format(snd_usb_substream_t *subs, struct audioformat *fmt)
subs->syncpipe = usb_rcvisocpipe(dev, ep);
else
subs->syncpipe = usb_sndisocpipe(dev, ep);
subs->syncinterval = get_endpoint(alts, 1)->bRefresh;
if (get_endpoint(alts, 1)->bLength >= USB_DT_ENDPOINT_AUDIO_SIZE &&
get_endpoint(alts, 1)->bRefresh >= 1 &&
get_endpoint(alts, 1)->bRefresh <= 9)
subs->syncinterval = get_endpoint(alts, 1)->bRefresh;
else
subs->syncinterval = 1;
}
/* always fill max packet size */