Patch "ALSA: usb-audio: Clear fixed clock rate at closing EP" has been added to the 5.15-stable tree

[Sasha Levin <sashal@xxxxxxxxxx>]

This is a note to let you know that I've just added the patch titled

    ALSA: usb-audio: Clear fixed clock rate at closing EP

to the 5.15-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     alsa-usb-audio-clear-fixed-clock-rate-at-closing-ep.patch
and it can be found in the queue-5.15 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.



commit a0573be416ef827a9a82df1737196e584fd0af79
Author: Takashi Iwai <tiwai@xxxxxxx>
Date:   Wed Sep 7 12:04:21 2022 +0200

    ALSA: usb-audio: Clear fixed clock rate at closing EP
    
    [ Upstream commit 809f44a0cc5ad4b1209467a6287f8ac0eb49d393 ]
    
    The recent commit c11117b634f4 ("ALSA: usb-audio: Refcount multiple
    accesses on the single clock") tries to manage the clock rate shared
    by several endpoints.  This was intended for avoiding the unmatched
    rate by a different endpoint, but unfortunately, it introduced a
    regression for PulseAudio and pipewire, too; those applications try to
    probe the multiple possible rates (44.1k and 48kHz) and setting up the
    normal rate fails but only the last rate is applied.
    
    The cause is that the last sample rate is still left to the clock
    reference even after closing the endpoint, and this value is still
    used at the next open.  It happens only when applications set up via
    PCM prepare but don't start/stop the stream; the rate is reset when
    the stream is stopped, but it's not cleared at close.
    
    This patch addresses the issue above, simply by clearing the rate set
    in the clock reference at the last close of each endpoint.
    
    Fixes: c11117b634f4 ("ALSA: usb-audio: Refcount multiple accesses on the single clock")
    Reported-by: Jason A. Donenfeld <Jason@xxxxxxxxx>
    Tested-by: Jason A. Donenfeld <Jason@xxxxxxxxx>
    Cc: <stable@xxxxxxxxxxxxxxx>
    Link: https://lore.kernel.org/all/YxXIWv8dYmg1tnXP@xxxxxxxxx/
    Link: https://gitlab.freedesktop.org/pipewire/pipewire/-/issues/2620
    Link: https://lore.kernel.org/r/20220907100421.6443-1-tiwai@xxxxxxx
    Signed-off-by: Takashi Iwai <tiwai@xxxxxxx>
    Stable-dep-of: 7822baa844a8 ("ALSA: usb-audio: add quirk for RODE NT-USB+")
    Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>

diff --git a/sound/usb/endpoint.c b/sound/usb/endpoint.c
index 803053d4c9dbc..13c0264881499 100644
--- a/sound/usb/endpoint.c
+++ b/sound/usb/endpoint.c
@@ -932,6 +932,8 @@ 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;
 		ep->iface = 0;
 		ep->altsetting = 0;
 		ep->cur_audiofmt = NULL;