[alsa-devel] [PATCH] sound/usb/card.c: clear chip->probing on error exit

Thomas Pfaff tpfaff at gmx.net
Thu Sep 22 18:26:06 CEST 2011

The Terratec Aureon 5.1 USB sound card support is broken since kernel 
2.6.39 introduced power management support for USB sound cards that added 
a probing flag in struct snd_usb_audio.

During the probe of the card it gives following error message :

usb 7-2: new full speed USB device number 2 using uhci_hcd
cannot find UAC_HEADER
snd-usb-audio: probe of 7-2:1.3 failed with error -5
input: USB Audio as 
generic-usb 0003:0CCD:0028.0001: input: USB HID v1.00 Device [USB Audio] 
on usb-0000:00:1d.1-2/input3

I can not comment about that "cannot find UAC_HEADER" error, but until 
2.6.38 the card worked anyway.
With 2.6.39 chip->probing remains 1 on error exit, and any later ioctl 
stops in snd_usb_autoresume with -ENODEV.

Signed-off-by: Thomas Pfaff <tpfaff at gmx.net>
diff -urp a/sound/usb/card.c b/sound/usb/card.c
--- a/sound/usb/card.c	2011-09-22 08:42:29.138247328 +0200
+++ b/sound/usb/card.c	2011-09-22 09:02:09.382079980 +0200
@@ -532,6 +532,7 @@ snd_usb_audio_probe(struct usb_device *d
 	if (chip && !chip->num_interfaces)
+	chip->probing = 0;
 	return NULL;

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