[alsa-devel] [PATCH] snd-usb-audio: explicitly match Logitech QuickCam

[Alan Stern]

On Mon, 30 Apr 2007, Daniel Drake wrote:

> Commit 93c8bf45e083b89dffe3a708363c15c1b220c723 modified the USB device
> matching behaviour to ignore interface class matches if the device class
> is vendor-specific.
> 
> This patch adds an explicit ID match for the Logitech QuickCam Messenger,
> which has a vendor specific device class (but standards-compliant audio
> interfaces).
> 
> This fixes a 2.6.20 regression where the audio component of this device was
> no longer usable.
> 
> http://bugs.gentoo.org/show_bug.cgi?id=175715
> https://bugs.launchpad.net/ubuntu/+source/linux-source-2.6.20/+bug/93822
> https://bugtrack.alsa-project.org/alsa-bug/view.php?id=3040
> 
> Based on a patch from sergiom
> 
> Signed-off-by: Daniel Drake <dsd at gentoo.org>
> 
> Index: linux/sound/usb/usbquirks.h
> ===================================================================
> --- linux.orig/sound/usb/usbquirks.h
> +++ linux/sound/usb/usbquirks.h
> @@ -40,6 +40,21 @@
>  	.bInterfaceClass = USB_CLASS_VENDOR_SPEC
>  
>  /*
> + * Logitech QuickCam: bDeviceClass is vendor-specific, so generic interface
> + * class matches do not take effect without an explicit ID match.
> + */
> +
> +{
> +	.match_flags = USB_DEVICE_ID_MATCH_DEVICE |
> +		       USB_DEVICE_ID_MATCH_INT_CLASS |
> +		       USB_DEVICE_ID_MATCH_INT_SUBCLASS,
> +	.idVendor = 0x046d,
> +	.idProduct = 0x08f0,
> +	.bInterfaceClass = USB_CLASS_AUDIO,
> +	.bInterfaceSubClass = USB_SUBCLASS_AUDIO_CONTROL
> +},
> +
> +/*
>   * Yamaha devices
>   */

This ought to fix the problem.

You might want to consider adding a macro to include/linux/usb.h to handle
cases like this.  Something like USB_DEVICE_AND_INTERFACE_INFO() -- it
would make life easier for other people in the future when faced with the
same problem.

Alan Stern