Commit 4974b795 authored by Takashi Iwai's avatar Takashi Iwai
Browse files

ALSA: usb-audio: Don't call usb_set_interface() at trigger callback 



The PCM trigger callback is atomic, hence we must not call a function
like usb_set_interface() there.  Calling it from there would lead to a
kernel Oops.

Fix it by moving the usb_set_interface() call to set_sync_endpoint().

Also, apply the snd_usb_set_interface_quirk() for consistency, too.

Tested-by: default avatarKeith Milner <kamilner@superlative.org>
Tested-by: default avatarDylan Robinson <dylan_robinson@motu.com>
Link: https://lore.kernel.org/r/20201123085347.19667-3-tiwai@suse.de


Signed-off-by: default avatarTakashi Iwai <tiwai@suse.de>
parent bc4e94aa

sound/usb/pcm.c

+13 −15
Original line number Diff line number Diff line
@@ -232,21 +232,6 @@ static int start_endpoints(struct snd_usb_substream *subs) 
	    !test_and_set_bit(SUBSTREAM_FLAG_SYNC_EP_STARTED, &subs->flags)) {

		struct snd_usb_endpoint *ep = subs->sync_endpoint;



		if (subs->data_endpoint->iface != subs->sync_endpoint->iface ||

		    subs->data_endpoint->altsetting != subs->sync_endpoint->altsetting) {

			err = usb_set_interface(subs->dev,

						subs->sync_endpoint->iface,

						subs->sync_endpoint->altsetting);

			if (err < 0) {

				clear_bit(SUBSTREAM_FLAG_SYNC_EP_STARTED, &subs->flags);

				dev_err(&subs->dev->dev,

					   "%d:%d: cannot set interface (%d)\n",

					   subs->sync_endpoint->iface,

					   subs->sync_endpoint->altsetting, err);

				return -EIO;

			}

		}



		dev_dbg(&subs->dev->dev, "Starting sync EP @%p\n", ep);



		ep->sync_slave = subs->data_endpoint;
@@ -530,6 +515,19 @@ static int set_sync_endpoint(struct snd_usb_substream *subs, 


	subs->data_endpoint->sync_master = subs->sync_endpoint;



	if (subs->data_endpoint->iface != subs->sync_endpoint->iface ||

	    subs->data_endpoint->altsetting != subs->sync_endpoint->altsetting) {

		err = usb_set_interface(subs->dev,

					subs->sync_endpoint->iface,

					subs->sync_endpoint->altsetting);

		if (err < 0)

			return err;

		dev_dbg(&dev->dev, "setting usb interface %d:%d\n",

			subs->sync_endpoint->iface,

			subs->sync_endpoint->altsetting);

		snd_usb_set_interface_quirk(dev);

	}



	return 0;

}