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Message-ID: <20111210194539.GF16692@amd.home.annexia.org>
Date: Sat, 10 Dec 2011 19:45:39 +0000
From: "Richard W.M. Jones" <rjones@...hat.com>
To: alsa-devel@...a-project.org
Cc: Tom Walder <tom.walder@...il.com>, linux-kernel@...r.kernel.org
Subject: [PATCH] Jabra SPEAK 410 USB - no audio playback
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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View attachment "linux-3.1.fc16-jabra.patch" of type "text/plain" (927 bytes)
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