[ 060/104] ALSA: usb-audio: Fix autopm error during probing

Greg Kroah-Hartman
2013-05-06T23:13:50Z

From: Takashi Iwai <tiwai@suse.de>

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@mixxx.org>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
sound/usb/card.c | 4 +++-
1 file changed, 3 insertions(+), 1 deletion(-)

--- a/sound/usb/card.c
+++ b/sound/usb/card.c
@@ -612,7 +612,9 @@ int snd_usb_autoresume(struct snd_usb_au
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);