From: Takashi Iwai tiwai@suse.de
[ Upstream commit 9a737e7f8b371e97eb649904276407cee2c9cf30 ]
We fixed the bug introduced by the patch for managing the shared clocks at the commit 809f44a0cc5a ("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: 809f44a0cc5a ("ALSA: usb-audio: Clear fixed clock rate at closing EP") Fixes: c11117b634f4 ("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 Signed-off-by: Sasha Levin sashal@kernel.org --- sound/usb/endpoint.c | 11 +++++++---- 1 file changed, 7 insertions(+), 4 deletions(-)
--- a/sound/usb/endpoint.c +++ b/sound/usb/endpoint.c @@ -39,6 +39,7 @@ struct snd_usb_iface_ref { struct snd_usb_clock_ref { unsigned char clock; atomic_t locked; + int opened; int rate; struct list_head list; }; @@ -802,6 +803,7 @@ snd_usb_endpoint_open(struct snd_usb_aud ep = NULL; goto unlock; } + ep->clock_ref->opened++; }
ep->cur_audiofmt = fp; @@ -925,8 +927,10 @@ void snd_usb_endpoint_close(struct snd_u 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; @@ -1633,8 +1637,7 @@ void snd_usb_endpoint_stop(struct snd_us 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); } }