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Commit 342cda29 authored by Clemens Ladisch's avatar Clemens Ladisch Committed by Takashi Iwai
Browse files

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



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: default avatarJeremy Rosen <jeremy.rosen@openwide.fr>
Tested-by: default avatarJeremy Rosen <jeremy.rosen@openwide.fr>
Cc: <stable@vger.kernel.org>
Signed-off-by: default avatarClemens Ladisch <clemens@ladisch.de>
Signed-off-by: default avatarTakashi Iwai <tiwai@suse.de>
parent d81bf8cf

sound/usb/card.c

+20 −2
Original line number Diff line number Diff line
@@ -147,14 +147,32 @@ 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) {