[PATCH 4.14 009/101] ALSA: usb-audio: Fix parsing descriptor of UAC2 processing unit

[Greg Kroah-Hartman <gregkh@linuxfoundation.org>]

4.14-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Kirill Marinushkin <k.marinushkin@gmail.com>

commit a6618f4aedb2b60932d766bd82ae7ce866e842aa upstream.

Currently, the offsets in the UAC2 processing unit descriptor are
calculated incorrectly. It causes an issue when connecting the device which
provides such a feature:

~~~~
[84126.724420] usb 1-1.3.1: invalid Processing Unit descriptor (id 18)
~~~~

After this patch is applied, the UAC2 processing unit inits w/o this error.

Fixes: 23caaf19b11e ("ALSA: usb-mixer: Add support for Audio Class v2.0")
Signed-off-by: Kirill Marinushkin <k.marinushkin@gmail.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 include/uapi/linux/usb/audio.h |    4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

--- a/include/uapi/linux/usb/audio.h
+++ b/include/uapi/linux/usb/audio.h
@@ -370,7 +370,7 @@ static inline __u8 uac_processing_unit_b
 {
 	return (protocol == UAC_VERSION_1) ?
 		desc->baSourceID[desc->bNrInPins + 4] :
-		desc->baSourceID[desc->bNrInPins + 6];
+		2; /* in UAC2, this value is constant */
 }
 
 static inline __u8 *uac_processing_unit_bmControls(struct uac_processing_unit_descriptor *desc,
@@ -378,7 +378,7 @@ static inline __u8 *uac_processing_unit_
 {
 	return (protocol == UAC_VERSION_1) ?
 		&desc->baSourceID[desc->bNrInPins + 5] :
-		&desc->baSourceID[desc->bNrInPins + 7];
+		&desc->baSourceID[desc->bNrInPins + 6];
 }
 
 static inline __u8 uac_processing_unit_iProcessing(struct uac_processing_unit_descriptor *desc,