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ALSA: usb-audio: work around Android accessory firmware bug

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commit 342cda2934 upstream.

When the Android firmware enables the audio interfaces in accessory
mode, it always declares in the control interface's baInterfaceNr array
that interfaces 0 and 1 belong to the audio function.  However, the
accessory interface itself, if also enabled, already is at index 0 and
shifts the actual audio interface numbers to 1 and 2, which prevents the
PCM streaming interface from being seen by the host driver.

To get the PCM interface interface to work, detect when the descriptors
point to the (for this driver useless) accessory interface, and redirect
to the correct one.

Reported-by: Jeremy Rosen <jeremy.rosen@openwide.fr>
Tested-by: Jeremy Rosen <jeremy.rosen@openwide.fr>
Signed-off-by: Clemens Ladisch <clemens@ladisch.de>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Clemens Ladisch 2013-06-15 11:21:09 +02:00 committed by Greg Kroah-Hartman
parent 2dc07099dd
commit e02a738d98
1 changed files with 20 additions and 2 deletions
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22
sound/usb/card.c
View file

@ -149,14 +149,32 @@ static int snd_usb_create_stream(struct snd_usb_audio *chip, int ctrlif, int int
return -EINVAL;
}
alts = &iface->altsetting[0];
altsd = get_iface_desc(alts);
/*
* Android with both accessory and audio interfaces enabled gets the
* interface numbers wrong.
*/
if ((chip->usb_id == USB_ID(0x18d1, 0x2d04) ||
chip->usb_id == USB_ID(0x18d1, 0x2d05)) &&
interface == 0 &&
altsd->bInterfaceClass == USB_CLASS_VENDOR_SPEC &&
altsd->bInterfaceSubClass == USB_SUBCLASS_VENDOR_SPEC) {
interface = 2;
iface = usb_ifnum_to_if(dev, interface);
if (!iface)
return -EINVAL;
alts = &iface->altsetting[0];
altsd = get_iface_desc(alts);
}
if (usb_interface_claimed(iface)) {
snd_printdd(KERN_INFO "%d:%d:%d: skipping, already claimed\n",
dev->devnum, ctrlif, interface);
return -EINVAL;
}
alts = &iface->altsetting[0];
altsd = get_iface_desc(alts);
if ((altsd->bInterfaceClass == USB_CLASS_AUDIO ||
altsd->bInterfaceClass == USB_CLASS_VENDOR_SPEC) &&
altsd->bInterfaceSubClass == USB_SUBCLASS_MIDISTREAMING) {