ALSA: usb-audio: fix feature unit parser for UAC2
Fix a small off-by-one bug which causes the feature unit to announce a
wrong number of channels. This leads to illegal requests sent to the
firmware eventually.
Signed-off-by: Daniel Mack <daniel@caiaq.de>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
diff --git a/sound/usb/mixer.c b/sound/usb/mixer.c
index 97dd176..03ce971 100644
--- a/sound/usb/mixer.c
+++ b/sound/usb/mixer.c
@@ -1126,7 +1126,7 @@
} else {
struct uac2_feature_unit_descriptor *ftr = _ftr;
csize = 4;
- channels = (hdr->bLength - 6) / 4;
+ channels = (hdr->bLength - 6) / 4 - 1;
bmaControls = ftr->bmaControls;
}