path: root/sound
diff options
authorDaniel Mack <daniel@caiaq.de>2010-09-02 17:13:15 +0800
committerTakashi Iwai <tiwai@suse.de>2010-09-02 11:58:37 +0200
commit7b6717e144de6592e614fd7fc3b914b6bf686a9d (patch)
tree14a5a0040455fc98136a7cdb6f8ec883d7d118c4 /sound
parent2bfc96a127bc1cc94d26bfaa40159966064f9c8c (diff)
ALSA: usb-audio: Assume first control interface is for audio
For devices with more than one control interface, let's assume the first one contains the audio controls. Unfortunately, there is no field in any of the descriptors to tell us whether a control interface is for audio or MIDI controls, so a better check is not easy to implement. On a composite device with audio and MIDI functions, for example, the code currently overwrites chip->ctrl_intf, causing operations on the control interface to fail if they are issued after the device probe. Signed-off-by: Daniel Mack <daniel@caiaq.de> Signed-off-by: Takashi Iwai <tiwai@suse.de>
Diffstat (limited to 'sound')
1 files changed, 7 insertions, 1 deletions
diff --git a/sound/usb/card.c b/sound/usb/card.c
index 9feb00c831a0..b443a33d31c9 100644
--- a/sound/usb/card.c
+++ b/sound/usb/card.c
@@ -465,7 +465,13 @@ static void *snd_usb_audio_probe(struct usb_device *dev,
goto __error;
- chip->ctrl_intf = alts;
+ /*
+ * For devices with more than one control interface, we assume the
+ * first contains the audio controls. We might need a more specific
+ * check here in the future.
+ */
+ if (!chip->ctrl_intf)
+ chip->ctrl_intf = alts;
if (err > 0) {
/* create normal USB audio interfaces */

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