[ALSA] usb audio suspend support

This patch implements suspend/resume support for USB audio devices.
It works with the microphone in my camera.

Signed-off-by: Oliver Neukum <oneukum@suse.de>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Jaroslav Kysela <perex@perex.cz>

2 files changed, 42 insertions, 0 deletions

diff --git a/sound/usb/usbaudio.c b/sound/usb/usbaudio.c
index 967b823eace0..c52461d4a042 100644
--- a/sound/usb/usbaudio.c
+++ b/sound/usb/usbaudio.c
@@ -2077,6 +2077,8 @@ int snd_usb_ctl_msg(struct usb_device *dev, unsigned int pipe, __u8 request,
 static int usb_audio_probe(struct usb_interface *intf,
                            const struct usb_device_id *id);
 static void usb_audio_disconnect(struct usb_interface *intf);
+static int usb_audio_suspend(struct usb_interface *intf, pm_message_t message);
+static int usb_audio_resume(struct usb_interface *intf);
 
 static struct usb_device_id usb_audio_ids [] = {
 #include "usbquirks.h"
@@ -2092,6 +2094,8 @@ static struct usb_driver usb_audio_driver = {
         .name =         "snd-usb-audio",
         .probe =        usb_audio_probe,
         .disconnect =   usb_audio_disconnect,
+        .suspend =      usb_audio_suspend,
+        .resume =       usb_audio_resume,
         .id_table =     usb_audio_ids,
 };
 
@@ -3654,6 +3658,43 @@ static void usb_audio_disconnect(struct usb_interface *intf)
                                  dev_get_drvdata(&intf->dev));
 }
 
+static int usb_audio_suspend(struct usb_interface *intf, pm_message_t message)
+{
+        struct snd_usb_audio *chip = dev_get_drvdata(&intf->dev);
+        struct list_head *p;
+        struct snd_usb_stream *as;
+
+        if (chip == (void *)-1L)
+                return 0;
+
+        snd_power_change_state(chip->card, SNDRV_CTL_POWER_D3hot);
+        if (!chip->num_suspended_intf++) {
+                list_for_each(p, &chip->pcm_list) {
+                        as = list_entry(p, struct snd_usb_stream, list);
+                        snd_pcm_suspend_all(as->pcm);
+                }
+        }
+
+        return 0;
+}
+
+static int usb_audio_resume(struct usb_interface *intf)
+{
+        struct snd_usb_audio *chip = dev_get_drvdata(&intf->dev);
+
+        if (chip == (void *)-1L)
+                return 0;
+        if (--chip->num_suspended_intf)
+                return 0;
+        /*
+         * ALSA leaves material resumption to user space
+         * we just notify
+         */
+
+        snd_power_change_state(chip->card, SNDRV_CTL_POWER_D0);
+
+        return 0;
+}
 
 static int __init snd_usb_audio_init(void)
 {
diff --git a/sound/usb/usbaudio.h b/sound/usb/usbaudio.h
index 2272f45a1867..7cf18c38dc42 100644
--- a/sound/usb/usbaudio.h
+++ b/sound/usb/usbaudio.h
@@ -126,6 +126,7 @@ struct snd_usb_audio {
         u32 usb_id;
         int shutdown;
         int num_interfaces;
+        int num_suspended_intf;
 
         struct list_head pcm_list;      /* list of pcm streams */
         int pcm_devs;