Commit 9902b303 authored by Takashi Iwai's avatar Takashi Iwai
Browse files

ALSA: usb-audio: Avoid unnecessary interface change at EP close 

We toggle USB interface at PCM prepare and reset at close.  When the
PCM isn't prepared, resetting again makes little sense.
Check the current altset and avoid unnecessary interface reset at EP
close.

Link: https://lore.kernel.org/r/20221009104212.18877-2-tiwai@suse.de


Signed-off-by: default avatarTakashi Iwai <tiwai@suse.de>
parent 556a11a0

sound/usb/endpoint.c

+5 −0
Original line number Diff line number Diff line
@@ -32,6 +32,7 @@ struct snd_usb_iface_ref { 
	unsigned char iface;

	bool need_setup;

	int opened;

	int altset;

	struct list_head list;

};
@@ -899,6 +900,9 @@ static int endpoint_set_interface(struct snd_usb_audio *chip, 
	int altset = set ? ep->altsetting : 0;

	int err;



	if (ep->iface_ref->altset == altset)

		return 0;



	usb_audio_dbg(chip, "Setting usb interface %d:%d for EP 0x%x\n",

		      ep->iface, altset, ep->ep_num);

	err = usb_set_interface(chip->dev, ep->iface, altset);
@@ -910,6 +914,7 @@ static int endpoint_set_interface(struct snd_usb_audio *chip, 


	if (chip->quirk_flags & QUIRK_FLAG_IFACE_DELAY)

		msleep(50);

	ep->iface_ref->altset = altset;

	return 0;

}