ALSA: snd-usb: add support for implicit feedback
Implicit feedback is a streaming mode that does not rely on dedicated
sync endpoints but uses the information provided by record streams to
clock output streams. Now that the streaming logic is decoupled from the
PCM streams, this is easy to implement.
Signed-off-by: Daniel Mack <zonque@gmail.com>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
diff --git a/sound/usb/pcm.c b/sound/usb/pcm.c
index 0f10783..2d3a04d 100644
--- a/sound/usb/pcm.c
+++ b/sound/usb/pcm.c
@@ -301,7 +301,7 @@
struct usb_interface *iface;
unsigned int ep, attr;
int is_playback = subs->direction == SNDRV_PCM_STREAM_PLAYBACK;
- int err;
+ int err, implicit_fb = 0;
iface = usb_ifnum_to_if(dev, fmt->iface);
if (WARN_ON(!iface))
@@ -326,25 +326,34 @@
* assume it as adaptive-out or sync-in.
*/
attr = fmt->ep_attr & USB_ENDPOINT_SYNCTYPE;
- if (((is_playback && attr == USB_ENDPOINT_SYNC_ASYNC) ||
- (! is_playback && attr == USB_ENDPOINT_SYNC_ADAPTIVE)) &&
- altsd->bNumEndpoints >= 2) {
- switch (subs->stream->chip->usb_id) {
- case USB_ID(0x0763, 0x2080): /* M-Audio FastTrack Ultra */
- case USB_ID(0x0763, 0x2081):
+
+ switch (subs->stream->chip->usb_id) {
+ case USB_ID(0x0763, 0x2080): /* M-Audio FastTrack Ultra */
+ case USB_ID(0x0763, 0x2081):
+ if (is_playback) {
+ implicit_fb = 1;
ep = 0x81;
iface = usb_ifnum_to_if(dev, 2);
+
+ if (!iface || iface->num_altsetting == 0)
+ return -EINVAL;
+
alts = &iface->altsetting[1];
goto add_sync_ep;
}
+ }
+ if (((is_playback && attr == USB_ENDPOINT_SYNC_ASYNC) ||
+ (!is_playback && attr == USB_ENDPOINT_SYNC_ADAPTIVE)) &&
+ altsd->bNumEndpoints >= 2) {
/* check sync-pipe endpoint */
/* ... and check descriptor size before accessing bSynchAddress
because there is a version of the SB Audigy 2 NX firmware lacking
the audio fields in the endpoint descriptors */
if ((get_endpoint(alts, 1)->bmAttributes & USB_ENDPOINT_XFERTYPE_MASK) != 0x01 ||
(get_endpoint(alts, 1)->bLength >= USB_DT_ENDPOINT_AUDIO_SIZE &&
- get_endpoint(alts, 1)->bSynchAddress != 0)) {
+ get_endpoint(alts, 1)->bSynchAddress != 0 &&
+ !implicit_fb)) {
snd_printk(KERN_ERR "%d:%d:%d : invalid synch pipe\n",
dev->devnum, fmt->iface, fmt->altsetting);
return -EINVAL;
@@ -352,16 +361,22 @@
ep = get_endpoint(alts, 1)->bEndpointAddress;
if (get_endpoint(alts, 0)->bLength >= USB_DT_ENDPOINT_AUDIO_SIZE &&
(( is_playback && ep != (unsigned int)(get_endpoint(alts, 0)->bSynchAddress | USB_DIR_IN)) ||
- (!is_playback && ep != (unsigned int)(get_endpoint(alts, 0)->bSynchAddress & ~USB_DIR_IN)))) {
+ (!is_playback && ep != (unsigned int)(get_endpoint(alts, 0)->bSynchAddress & ~USB_DIR_IN)) ||
+ ( is_playback && !implicit_fb))) {
snd_printk(KERN_ERR "%d:%d:%d : invalid synch pipe\n",
dev->devnum, fmt->iface, fmt->altsetting);
return -EINVAL;
}
+
+ implicit_fb = (get_endpoint(alts, 1)->bmAttributes & USB_ENDPOINT_USAGE_MASK)
+ == USB_ENDPOINT_USAGE_IMPLICIT_FB;
+
add_sync_ep:
subs->sync_endpoint = snd_usb_add_endpoint(subs->stream->chip,
alts, ep, !subs->direction,
- SND_USB_ENDPOINT_TYPE_SYNC);
-
+ implicit_fb ?
+ SND_USB_ENDPOINT_TYPE_DATA :
+ SND_USB_ENDPOINT_TYPE_SYNC);
if (!subs->sync_endpoint)
return -EINVAL;
