usb: gadget: u_audio: Add suspend call

Add exported method u_audio_suspend which sets stream status to
inactive and sends notifications. The method does not free any
resources.
Signed-off-by: Pavel Hofman <pavel.hofman@ivitera.com>
Link: https://lore.kernel.org/r/20220121155308.48794-9-pavel.hofman@ivitera.comSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/usb/gadget/function/u_audio.c

@@ -757,6 +757,15 @@ void u_audio_stop_playback(struct g_audio *audio_dev)
 }
 EXPORT_SYMBOL_GPL(u_audio_stop_playback);
 
+void u_audio_suspend(struct g_audio *audio_dev)
+{
+	struct snd_uac_chip *uac = audio_dev->uac;
+
+	set_active(&uac->p_prm, false);
+	set_active(&uac->c_prm, false);
+}
+EXPORT_SYMBOL_GPL(u_audio_suspend);
+
 int u_audio_get_volume(struct g_audio *audio_dev, int playback, s16 *val)
 {
 	struct snd_uac_chip *uac = audio_dev->uac;

drivers/usb/gadget/function/u_audio.h

@@ -130,4 +130,6 @@ int u_audio_set_volume(struct g_audio *g_audio, int playback, s16 val);
 int u_audio_get_mute(struct g_audio *g_audio, int playback, int *val);
 int u_audio_set_mute(struct g_audio *g_audio, int playback, int val);
 
+void u_audio_suspend(struct g_audio *g_audio);
+
 #endif /* __U_AUDIO_H */