[ 3.5.y.z extended stable ] Patch "ALSA: usb-audio: Fix autopm error during probing" has been added to staging queue

[Luis Henriques]

This is a note to let you know that I have just added a patch titled

    ALSA: usb-audio: Fix autopm error during probing

to the linux-3.5.y-queue branch of the 3.5.y.z extended stable tree 
which can be found at:

 http://kernel.ubuntu.com/git?p=ubuntu/linux.git;a=shortlog;h=refs/heads/linux-3.5.y-queue

If you, or anyone else, feels it should not be added to this tree, please 
reply to this email.

For more information about the 3.5.y.z tree, see
https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable

Thanks.
-Luis

------

>From 15bb89dc72bff91de10dd51110085aec22460257 Mon Sep 17 00:00:00 2001
From: Takashi Iwai <tiwai at suse.de>
Date: Thu, 25 Apr 2013 07:38:15 +0200
Subject: [PATCH] ALSA: usb-audio: Fix autopm error during probing
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

commit 60af3d037eb8c670dcce31401501d1271e7c5d95 upstream.

We've got strange errors in get_ctl_value() in mixer.c during
probing, e.g. on Hercules RMX2 DJ Controller:

  ALSA mixer.c:352 cannot get ctl value: req = 0x83, wValue = 0x201, wIndex = 0xa00, type = 4
  ALSA mixer.c:352 cannot get ctl value: req = 0x83, wValue = 0x200, wIndex = 0xa00, type = 4
  ....

It turned out that the culprit is autopm: snd_usb_autoresume() returns
-ENODEV when called during card->probing = 1.

Since the call itself during card->probing = 1 is valid, let's fix the
return value of snd_usb_autoresume() as success.

Reported-and-tested-by: Daniel Schürmann <daschuer at mixxx.org>
Signed-off-by: Takashi Iwai <tiwai at suse.de>
Signed-off-by: Luis Henriques <luis.henriques at canonical.com>
---
 sound/usb/card.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/sound/usb/card.c b/sound/usb/card.c
index b3f5ad4..aa25e04 100644
--- a/sound/usb/card.c
+++ b/sound/usb/card.c
@@ -619,7 +619,9 @@ int snd_usb_autoresume(struct snd_usb_audio *chip)
 	int err = -ENODEV;

 	down_read(&chip->shutdown_rwsem);
-	if (!chip->shutdown && !chip->probing)
+	if (chip->probing)
+		err = 0;
+	else if (!chip->shutdown)
 		err = usb_autopm_get_interface(chip->pm_intf);
 	up_read(&chip->shutdown_rwsem);

--
1.8.1.2