[alsa-devel] [PATCH] Jabra SPEAK 410 USB - no audio playback

[Richard W.M. Jones]

The attached patch fixes USB audio support for the Jabra SPEAK 410 USB.

The problem, as I understand it, is that the device contains a
Class-Specific Endpoint (CS_ENDPOINT) descriptor before the Endpoint
(ENDPOINT) descriptor.  The USB code all assumes that CS_ENDPOINT can
only appear after ENDPOINT.  Therefore the USB code divides up the
interface descriptor into "stuff before ENDPOINT" (in
interface->extra) and "stuff after ENDPOINT" (in
interface->endpoint[0]->extra).  For this device, this division does
not work.

You can see lsusb for my device here:
http://mailman.alsa-project.org/pipermail/alsa-devel/2011-December/047036.html
Notice the "** UNRECOGNIZED: 07 25 01 81 02 00 00" line which is the
CS_ENDPOINT descriptor.

The solution (which is a hack ...) is to also search interface->extra
looking for the missing descriptor.

For me, this fully enables the functions of this device.

Rich.

-- 
Richard Jones, Virtualization Group, Red Hat http://people.redhat.com/~rjones
Read my programming blog: http://rwmj.wordpress.com
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-------------- next part --------------
diff -uNrp kernel-3.1.fc16.orig/sound/usb/stream.c kernel-3.1.fc16.new/sound/usb/stream.c
--- kernel-3.1.fc16.orig/sound/usb/stream.c	2011-12-10 18:03:29.658729051 +0000
+++ kernel-3.1.fc16.new/sound/usb/stream.c	2011-12-10 18:08:41.468694907 +0000
@@ -164,6 +164,12 @@ static int parse_uac_endpoint_attributes
 
 	csep = snd_usb_find_desc(alts->endpoint[0].extra, alts->endpoint[0].extralen, NULL, USB_DT_CS_ENDPOINT);
 
+	/* Jabra SPEAK 410 USB has CS_ENDPOINT before ordinary ENDPOINT,
+	 * which confuses the USB descriptor parsing code.  Try looking
+	 * for CS_ENDPOINT in the interface->extra - RWMJ. */
+	if (!csep)
+		csep = snd_usb_find_desc(alts->extra, alts->extralen, NULL, USB_DT_CS_ENDPOINT);
+
 	/* Creamware Noah has this descriptor after the 2nd endpoint */
 	if (!csep && altsd->bNumEndpoints >= 2)
 		csep = snd_usb_find_desc(alts->endpoint[1].extra, alts->endpoint[1].extralen, NULL, USB_DT_CS_ENDPOINT);