[PATCH 3.12 019/123] ALSA: usb-audio: Save mixer status only once at suspend

[Jiri Slaby]

From: Takashi Iwai <tiwai@xxxxxxx>

3.12-stable review patch.  If anyone has any objections, please let me know.

===============

commit 1c53e7253ed8769a00afa0f06777d731dbe1ba6f upstream.

The suspend callback of usb-audio driver may be called multiple times
per suspend when multiple USB interfaces are bound to a single sound
card instance.  In such a case, it's superfluous to save the mixer
values multiple times.  This patch fixes it by checking the counter.

Signed-off-by: Takashi Iwai <tiwai@xxxxxxx>
Signed-off-by: Jiri Slaby <jslaby@xxxxxxx>
---
 sound/usb/card.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/sound/usb/card.c b/sound/usb/card.c
index 3ab9fc47da09..ca55e033cf9d 100644
--- a/sound/usb/card.c
+++ b/sound/usb/card.c
@@ -705,8 +705,9 @@ static int usb_audio_suspend(struct usb_interface *intf, pm_message_t message)
 			chip->autosuspended = 1;
 	}
 
-	list_for_each_entry(mixer, &chip->mixer_list, list)
-		snd_usb_mixer_suspend(mixer);
+	if (chip->num_suspended_intf == 1)
+		list_for_each_entry(mixer, &chip->mixer_list, list)
+			snd_usb_mixer_suspend(mixer);
 
 	return 0;
 }
-- 
2.5.0

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