[PATCH] ALSA: usb-audio: Fix parsing descriptor of UAC2 processing unit

[Kirill Marinushkin <k.marinushkin@gmail.com>]

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: 5e1ddb481776 ("UAPI: (Scripted) Disintegrate include/linux/usb")
Signed-off-by: Kirill Marinushkin <k.marinushkin@gmail.com>
Cc: Mark Brown <broonie@kernel.org>
Cc: Jaroslav Kysela <perex@perex.cz>
Cc: Takashi Iwai <tiwai@suse.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Felipe Balbi <felipe.balbi@linux.intel.com>
Cc: Philippe Ombredanne <pombredanne@nexb.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Ruslan Bilovol <ruslan.bilovol@gmail.com>
Cc: linux-kernel@vger.kernel.org
Cc: alsa-devel@alsa-project.org
---
 include/uapi/linux/usb/audio.h | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/include/uapi/linux/usb/audio.h b/include/uapi/linux/usb/audio.h
index 17a022c5b414..da3315ed1bcd 100644
--- a/include/uapi/linux/usb/audio.h
+++ b/include/uapi/linux/usb/audio.h
@@ -370,7 +370,7 @@ static inline __u8 uac_processing_unit_bControlSize(struct uac_processing_unit_d
 {
 	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_bmControls(struct uac_processing_unit_de
 {
 	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,
-- 
2.13.6