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Subject[PATCH 3.4 103/134] ALSA: usb-audio: skip UAC2 EFFECT_UNIT
Date
3.4-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Eldad Zack <eldad@fogrefinery.com>

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@fogrefinery.com>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
Cc: Weng Meiling <wengmeiling.weng@huawei.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
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 */



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