Commit 9a737e7f authored by Takashi Iwai's avatar Takashi Iwai
Browse files

ALSA: usb-audio: Properly refcounting clock rate 

We fixed the bug introduced by the patch for managing the shared
clocks at the commit 809f44a0 ("ALSA: usb-audio: Clear fixed clock
rate at closing EP"), but it was merely a workaround.  By this change,
the clock reference rate is cleared at each EP close, hence the still
remaining EP may need a re-setup of rate unnecessarily.

This patch introduces the proper refcounting for the clock reference
object so that the clock setup is done only when needed.

Fixes: 809f44a0 ("ALSA: usb-audio: Clear fixed clock rate at closing EP")
Fixes: c11117b6 ("ALSA: usb-audio: Refcount multiple accesses on the single clock")
Link: https://lore.kernel.org/r/20220920181126.4912-1-tiwai@suse.de


Signed-off-by: default avatarTakashi Iwai <tiwai@suse.de>
parent 2be79d58

sound/usb/endpoint.c

+7 −4
Original line number Diff line number Diff line
@@ -39,6 +39,7 @@ struct snd_usb_iface_ref { 
struct snd_usb_clock_ref {

	unsigned char clock;

	atomic_t locked;

	int opened;

	int rate;

	bool need_setup;

	struct list_head list;
@@ -803,6 +804,7 @@ snd_usb_endpoint_open(struct snd_usb_audio *chip, 
				ep = NULL;

				goto unlock;

			}

			ep->clock_ref->opened++;

		}



		ep->cur_audiofmt = fp;
@@ -926,8 +928,10 @@ void snd_usb_endpoint_close(struct snd_usb_audio *chip, 
		endpoint_set_interface(chip, ep, false);



	if (!--ep->opened) {

		if (ep->clock_ref && !atomic_read(&ep->clock_ref->locked))

		if (ep->clock_ref) {

			if (!--ep->clock_ref->opened)

				ep->clock_ref->rate = 0;

		}

		ep->iface = 0;

		ep->altsetting = 0;

		ep->cur_audiofmt = NULL;
@@ -1649,8 +1653,7 @@ void snd_usb_endpoint_stop(struct snd_usb_endpoint *ep, bool keep_pending) 
			WRITE_ONCE(ep->sync_source->sync_sink, NULL);

		stop_urbs(ep, false, keep_pending);

		if (ep->clock_ref)

			if (!atomic_dec_return(&ep->clock_ref->locked))

				ep->clock_ref->rate = 0;

			atomic_dec(&ep->clock_ref->locked);

	}

}