[ 3.5.y.z extended stable ] Patch "ALSA: ua101, usx2y: fix broken MIDI output" has been added to staging queue

[Herton Ronaldo Krzesinski]

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

    ALSA: ua101, usx2y: fix broken MIDI output

to the linux-3.5.y-queue branch of the 3.5.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-3.5.y-queue

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

For more information about the 3.5.y.z tree, see
https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable

Thanks.
-Herton

------

>From 77d8369a28fe58fa52213d67c763b877f8c11801 Mon Sep 17 00:00:00 2001
From: Clemens Ladisch <clemens at ladisch.de>
Date: Wed, 31 Oct 2012 16:35:30 +0100
Subject: [PATCH] ALSA: ua101, usx2y: fix broken MIDI output

commit e99ddfde6ae0dd2662bb40435696002b590e4057 upstream.

Commit 88a8516a2128 (ALSA: usbaudio: implement USB autosuspend) added
autosuspend code to all files making up the snd-usb-audio driver.
However, midi.c is part of snd-usb-lib and is also used by other
drivers, not all of which support autosuspend.  Thus, calls to
usb_autopm_get_interface() could fail, and this unexpected error would
result in the MIDI output being completely unusable.

Make it work by ignoring the error that is expected with drivers that do
not support autosuspend.

Reported-by: Colin Fletcher <colin.m.fletcher at googlemail.com>
Reported-by: Devin Venable <venable.devin at gmail.com>
Reported-by: Dr Nick Bailey <nicholas.bailey at glasgow.ac.uk>
Reported-by: Jannis Achstetter <jannis_achstetter at web.de>
Reported-by: Rui Nuno Capela <rncbc at rncbc.org>
Cc: Oliver Neukum <oliver at neukum.org>
Signed-off-by: Clemens Ladisch <clemens at ladisch.de>
Signed-off-by: Herton Ronaldo Krzesinski <herton.krzesinski at canonical.com>
---
 sound/usb/midi.c |    8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/sound/usb/midi.c b/sound/usb/midi.c
index c83f614..eeefbce 100644
--- a/sound/usb/midi.c
+++ b/sound/usb/midi.c
@@ -148,6 +148,7 @@ struct snd_usb_midi_out_endpoint {
 		struct snd_usb_midi_out_endpoint* ep;
 		struct snd_rawmidi_substream *substream;
 		int active;
+		bool autopm_reference;
 		uint8_t cable;		/* cable number << 4 */
 		uint8_t state;
 #define STATE_UNKNOWN	0
@@ -1076,7 +1077,8 @@ static int snd_usbmidi_output_open(struct snd_rawmidi_substream *substream)
 		return -ENXIO;
 	}
 	err = usb_autopm_get_interface(umidi->iface);
-	if (err < 0)
+	port->autopm_reference = err >= 0;
+	if (err < 0 && err != -EACCES)
 		return -EIO;
 	substream->runtime->private_data = port;
 	port->state = STATE_UNKNOWN;
@@ -1087,9 +1089,11 @@ static int snd_usbmidi_output_open(struct snd_rawmidi_substream *substream)
 static int snd_usbmidi_output_close(struct snd_rawmidi_substream *substream)
 {
 	struct snd_usb_midi* umidi = substream->rmidi->private_data;
+	struct usbmidi_out_port *port = substream->runtime->private_data;

 	substream_open(substream, 0);
-	usb_autopm_put_interface(umidi->iface);
+	if (port->autopm_reference)
+		usb_autopm_put_interface(umidi->iface);
 	return 0;
 }

--
1.7.9.5