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ALSA: usb-audio: Properly refcounting clock rate

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We fixed the bug introduced by the patch for managing the shared
clocks at the commit 809f44a0cc ("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: 809f44a0cc ("ALSA: usb-audio: Clear fixed clock rate at closing EP")
Fixes: c11117b634 ("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: Takashi Iwai <tiwai@suse.de>
This commit is contained in:
Takashi Iwai 2022-09-20 20:11:26 +02:00
parent 2be79d5864
commit 9a737e7f8b
1 changed files with 7 additions and 4 deletions
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11
sound/usb/endpoint.c
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@ -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))
ep->clock_ref->rate = 0;
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);
}
}