ALSA: usb-audio: Avoid unnecessary interface re-setup

The current endpoint handling assumed (more or less) a unique 1:1
relation between the endpoint and the iface/altset.  The exception was
the sync EP without the implicit feedback which has usually the
secondary EP of the same altset.  This works fine for most devices,
but it turned out that some unusual devices like Pinoeer's ones have
both playback and capture endpoints in the same iface/altsetting and
use both for the implicit feedback mode.  For handling such a case, we
need to extend the endpoint management to take the shared interface
into account.

This patch does that: it adds a new object snd_usb_iface_ref for
managing the reference counts of the each USB interface that is used
by each endpoint.  The interface setup is performed only once for the
(sharing) endpoints, and the doubly initialization is avoided.

Along with this, the resource release of endpoints and interface
refcounts are put into a single function, snd_usb_endpoint_free_all()
instead of looping in the caller side.

Fixes: bf6313a0ff76 ("ALSA: usb-audio: Refactor endpoint management")
Link: https://lore.kernel.org/r/20210108075219.21463-4-tiwai@suse.de
Signed-off-by: Takashi Iwai <tiwai@suse.de>

1 files changed, 1 insertions, 1 deletions

diff --git a/sound/usb/endpoint.h b/sound/usb/endpoint.h
index 11e3bb839fd7..eea4ca49876d 100644
--- a/sound/usb/endpoint.h
+++ b/sound/usb/endpoint.h
@@ -42,7 +42,7 @@ void snd_usb_endpoint_sync_pending_stop(struct snd_usb_endpoint *ep);
 void snd_usb_endpoint_suspend(struct snd_usb_endpoint *ep);
 int  snd_usb_endpoint_activate(struct snd_usb_endpoint *ep);
 void snd_usb_endpoint_release(struct snd_usb_endpoint *ep);
-void snd_usb_endpoint_free(struct snd_usb_endpoint *ep);
+void snd_usb_endpoint_free_all(struct snd_usb_audio *chip);
 
 int snd_usb_endpoint_implicit_feedback_sink(struct snd_usb_endpoint *ep);
 int snd_usb_endpoint_next_packet_size(struct snd_usb_endpoint *ep,