[PATCH 3.16.y-ckt 23/71] ALSA: usb-audio: fix missing input volume controls in MAYA44 USB(+)

[Luis Henriques]

3.16.7-ckt14 -stable review patch.  If anyone has any objections, please let me know.

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

From: Clemens Ladisch <clemens@xxxxxxxxxx>

commit ea114fc27dc0cb9a550b6add5426720feb66262a upstream.

The driver worked around an error in the MAYA44 USB(+)'s mixer unit
descriptor by aborting before parsing the missing field.  However,
aborting parsing too early prevented parsing of the other units
connected to this unit, so the capture mixer controls would be missing.

Fix this by moving the check for this descriptor error after the parsing
of the unit's input pins.

Reported-by: nightmixes <nightmixes@xxxxxxxxx>
Tested-by: nightmixes <nightmixes@xxxxxxxxx>
Signed-off-by: Clemens Ladisch <clemens@xxxxxxxxxx>
Signed-off-by: Takashi Iwai <tiwai@xxxxxxx>
Signed-off-by: Luis Henriques <luis.henriques@xxxxxxxxxxxxx>
---
 sound/usb/mixer.c | 9 +++------
 1 file changed, 3 insertions(+), 6 deletions(-)

diff --git a/sound/usb/mixer.c b/sound/usb/mixer.c
index b4283660d430..f6d4967a652a 100644
--- a/sound/usb/mixer.c
+++ b/sound/usb/mixer.c
@@ -1583,12 +1583,6 @@ static int parse_audio_mixer_unit(struct mixer_build *state, int unitid,
 			      unitid);
 		return -EINVAL;
 	}
-	/* no bmControls field (e.g. Maya44) -> ignore */
-	if (desc->bLength <= 10 + input_pins) {
-		usb_audio_dbg(state->chip, "MU %d has no bmControls field\n",
-			      unitid);
-		return 0;
-	}
 
 	num_ins = 0;
 	ich = 0;
@@ -1596,6 +1590,9 @@ static int parse_audio_mixer_unit(struct mixer_build *state, int unitid,
 		err = parse_audio_unit(state, desc->baSourceID[pin]);
 		if (err < 0)
 			continue;
+		/* no bmControls field (e.g. Maya44) -> ignore */
+		if (desc->bLength <= 10 + input_pins)
+			continue;
 		err = check_input_term(state, desc->baSourceID[pin], &iterm);
 		if (err < 0)
 			return err;
--
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