[ 3.8.y.z extended stable ] Patch "ALSA: usb-audio: work around Android accessory firmware bug" has been added to staging queue

Kamal Mostafa kamal at canonical.com
Tue Jun 25 22:20:05 UTC 2013


This is a note to let you know that I have just added a patch titled

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

to the linux-3.8.y-queue branch of the 3.8.y.z extended stable tree 
which can be found at:

 http://kernel.ubuntu.com/git?p=ubuntu/linux.git;a=shortlog;h=refs/heads/linux-3.8.y-queue

This patch is scheduled to be released in version 3.8.13.4.

If you, or anyone else, feels it should not be added to this tree, please 
reply to this email.

For more information about the 3.8.y.z tree, see
https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable

Thanks.
-Kamal

------

>From 7cca6389ab441b800313c356818cc445a828b395 Mon Sep 17 00:00:00 2001
From: Clemens Ladisch <clemens at ladisch.de>
Date: Sat, 15 Jun 2013 11:21:09 +0200
Subject: ALSA: usb-audio: work around Android accessory firmware bug

commit 342cda29343a6272c630f94ed56810a76740251b 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 at openwide.fr>
Tested-by: Jeremy Rosen <jeremy.rosen at openwide.fr>
Signed-off-by: Clemens Ladisch <clemens at ladisch.de>
Signed-off-by: Takashi Iwai <tiwai at suse.de>
Signed-off-by: Kamal Mostafa <kamal at canonical.com>
---
 sound/usb/card.c | 22 ++++++++++++++++++++--
 1 file changed, 20 insertions(+), 2 deletions(-)

diff --git a/sound/usb/card.c b/sound/usb/card.c
index a9d5779..3e4565f 100644
--- a/sound/usb/card.c
+++ b/sound/usb/card.c
@@ -144,14 +144,32 @@ 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) {
--
1.8.1.2





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