ALSA: usb-audio: skip UAC2 EFFECT_UNIT

Current code mishandles the case where the device is a UAC2
and the bDescriptorSubtype is a UAC2 Effect Unit (0x07).
It tries to parse it as a Processing Unit (which is similar to two
other UAC1 units with overlapping subtypes), but since the structure
is different (See: 4.7.2.10, 4.7.2.11 in UAC2 standard), the parsing
is done incorrectly and prevents the device from initializing.
For now, just ignore the unit.

Signed-off-by: Eldad Zack <eldad@fogrefinery.com>
Signed-off-by: Takashi Iwai <tiwai@suse.de>

diff --git a/sound/usb/mixer.c b/sound/usb/mixer.c
index b0fc6ae..4eacbe2 100644 (file)
--- a/sound/usb/mixer.c
+++ b/sound/usb/mixer.c
@@ -723,8 +723,19 @@ static int check_input_term(struct mixer_build *state, int id, struct usb_audio_
                        return 0;
                }
                case UAC1_PROCESSING_UNIT:
-               case UAC1_EXTENSION_UNIT: {
+               case UAC1_EXTENSION_UNIT:
+               /* UAC2_PROCESSING_UNIT_V2 */
+               /* UAC2_EFFECT_UNIT */ {
                        struct uac_processing_unit_descriptor *d = p1;
+
+                       if (state->mixer->protocol == UAC_VERSION_2 &&
+                               hdr[2] == UAC2_EFFECT_UNIT) {
+                               /* UAC2/UAC1 unit IDs overlap here in an
+                                * uncompatible way. Ignore this unit for now.
+                                */
+                               return 0;
+                       }
+
                        if (d->bNrInPins) {
                                id = d->baSourceID[0];
                                break; /* continue to parse */