This is a note to let you know that I've just added the patch titled
ALSA: usb-audio: skip UAC2 EFFECT_UNIT
to the 3.4-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
alsa-usb-audio-skip-uac2-effect_unit.patch
and it can be found in the queue-3.4 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From 2ca3bc2ba143bdaf753b88310455074a3d2ed7e4 Mon Sep 17 00:00:00 2001
From: Eldad Zack <eldad@xxxxxxxxxxxxxxx>
Date: Wed, 28 Nov 2012 23:55:36 +0100
Subject: ALSA: usb-audio: skip UAC2 EFFECT_UNIT
From: Eldad Zack <eldad@xxxxxxxxxxxxxxx>
commit 5dae5fd24071319bb67d3375217d5b0b6d16cb0b upstream.
Current code mishandles the case where the device is a UAC2
and the bDescriptorSubtype is a UAC2 Effect Unit (0x07).
It tries to parse it as a Processing Unit (which is similar to two
other UAC1 units with overlapping subtypes), but since the structure
is different (See: 4.7.2.10, 4.7.2.11 in UAC2 standard), the parsing
is done incorrectly and prevents the device from initializing.
For now, just ignore the unit.
Signed-off-by: Eldad Zack <eldad@xxxxxxxxxxxxxxx>
Signed-off-by: Takashi Iwai <tiwai@xxxxxxx>
Signed-off-by: Ben Hutchings <ben@xxxxxxxxxxxxxxx>
Cc: Weng Meiling <wengmeiling.weng@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
sound/usb/mixer.c | 13 ++++++++++++-
1 file changed, 12 insertions(+), 1 deletion(-)
--- a/sound/usb/mixer.c
+++ b/sound/usb/mixer.c
@@ -720,8 +720,19 @@ static int check_input_term(struct mixer
return 0;
}
case UAC1_PROCESSING_UNIT:
- case UAC1_EXTENSION_UNIT: {
+ case UAC1_EXTENSION_UNIT:
+ /* UAC2_PROCESSING_UNIT_V2 */
+ /* UAC2_EFFECT_UNIT */ {
struct uac_processing_unit_descriptor *d = p1;
+
+ if (state->mixer->protocol == UAC_VERSION_2 &&
+ hdr[2] == UAC2_EFFECT_UNIT) {
+ /* UAC2/UAC1 unit IDs overlap here in an
+ * uncompatible way. Ignore this unit for now.
+ */
+ return 0;
+ }
+
if (d->bNrInPins) {
id = d->baSourceID[0];
break; /* continue to parse */
Patches currently in stable-queue which might be from eldad@xxxxxxxxxxxxxxx are
queue-3.4/alsa-usb-audio-skip-uac2-effect_unit.patch
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