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| author | Thomas Pugliese <thomas.pugliese@gmail.com> | 2013-11-26 23:58:15 +0400 |
|---|---|---|
| committer | Takashi Iwai <tiwai@suse.de> | 2013-11-27 14:55:13 +0400 |
| commit | a93455e1c301ce2a4cae11682359fd2067a8fd30 (patch) | |
| tree | 2662f91999cdd6662b1229c96cee25cfd6473fa7 /sound/usb | |
| parent | 2fd3f170e5ba04acc60ee94b2c76ee166727c734 (diff) | |
| download | linux-a93455e1c301ce2a4cae11682359fd2067a8fd30.tar.xz | |
ALSA: usb: use multiple packets per urb for Wireless USB inbound audio
For Wireless USB audio devices, use multiple isoc packets per URB for
inbound endpoints with a datainterval < 5. This allows the WUSB host
controller to take advantage of bursting to service endpoints whose
logical polling interval is less than the 4ms minimum polling interval
limit in WUSB.
Signed-off-by: Thomas Pugliese <thomas.pugliese@gmail.com>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Diffstat (limited to 'sound/usb')
| -rw-r--r-- | sound/usb/endpoint.c | 16 |
1 files changed, 15 insertions, 1 deletions
diff --git a/sound/usb/endpoint.c b/sound/usb/endpoint.c index b9ba0fcc45df..83aabea259d7 100644 --- a/sound/usb/endpoint.c +++ b/sound/usb/endpoint.c @@ -636,8 +636,22 @@ static int data_ep_set_params(struct snd_usb_endpoint *ep, if (usb_pipein(ep->pipe) || snd_usb_endpoint_implicit_feedback_sink(ep)) { + urb_packs = packs_per_ms; + /* + * Wireless devices can poll at a max rate of once per 4ms. + * For dataintervals less than 5, increase the packet count to + * allow the host controller to use bursting to fill in the + * gaps. + */ + if (snd_usb_get_speed(ep->chip->dev) == USB_SPEED_WIRELESS) { + int interval = ep->datainterval; + while (interval < 5) { + urb_packs <<= 1; + ++interval; + } + } /* make capture URBs <= 1 ms and smaller than a period */ - urb_packs = min(max_packs_per_urb, packs_per_ms); + urb_packs = min(max_packs_per_urb, urb_packs); while (urb_packs > 1 && urb_packs * maxsize >= period_bytes) urb_packs >>= 1; ep->nurbs = MAX_URBS; |