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

[Daniel Drake]

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
  */