Merge branch 'usb-midi-fix-3.7' of git://git.alsa-project.org/alsa-kprivate into for-linus

Merge a regression fix for USB MIDI on non-standard usb-audio drivers
by Clemens.

1 files changed, 6 insertions, 2 deletions

diff --git a/sound/usb/midi.c b/sound/usb/midi.c
index c83f6143c0eb..eeefbce3873c 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;
 }