[ALSA] usb audio: Fix another Dallas quirk
Dallas USB speakers are buggy in more than one way. One of configs
they offer does not work at all.
Signed-off-by: Pavel Machek <pavel@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
diff --git a/sound/usb/usbaudio.c b/sound/usb/usbaudio.c
index 5c40c03..ff2e09a 100644
--- a/sound/usb/usbaudio.c
+++ b/sound/usb/usbaudio.c
@@ -2676,12 +2676,23 @@
int format;
struct audioformat *fp;
unsigned char *fmt, *csep;
+ int num;
dev = chip->dev;
/* parse the interface's altsettings */
iface = usb_ifnum_to_if(dev, iface_no);
- for (i = 0; i < iface->num_altsetting; i++) {
+
+ num = iface->num_altsetting;
+
+ /*
+ * Dallas DS4201 workaround: It presents 5 altsettings, but the last
+ * one misses syncpipe, and does not produce any sound.
+ */
+ if (chip->usb_id == USB_ID(0x04fa, 0x4201))
+ num = 4;
+
+ for (i = 0; i < num; i++) {
alts = &iface->altsetting[i];
altsd = get_iface_desc(alts);
/* skip invalid one */