This is a note to let you know that I've just added the patch titled
ALSA: usb-audio: Less restriction for low-latency playback mode
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-less-restriction-for-low-latency-playback-mode.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.
>From 53451b6da8271905941eb1eb369db152c4bd92f2 Mon Sep 17 00:00:00 2001
From: Takashi Iwai <tiwai@xxxxxxx>
Date: Mon, 11 Oct 2021 12:36:50 +0200
Subject: ALSA: usb-audio: Less restriction for low-latency playback mode
From: Takashi Iwai <tiwai@xxxxxxx>
commit 53451b6da8271905941eb1eb369db152c4bd92f2 upstream.
The recent support for the improved low-latency playback mode applied
the SNDRV_PCM_INFO_EXPLICIT_SYNC flag for the target streams, but this
was a slight overkill. The use of the flag above disables effectively
both PCM status and control mmaps, while basically what we want to
track is only about the appl_ptr update.
For less restriction, use a more proper flag,
SNDRV_PCM_INFO_SYNC_APPLPTR instead, which disables only the control
mmap.
Fixes: d5f871f89e21 ("ALSA: usb-audio: Improved lowlatency playback support")
Link: https://lore.kernel.org/r/20211011103650.10182-1-tiwai@xxxxxxx
Signed-off-by: Takashi Iwai <tiwai@xxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
sound/usb/pcm.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
--- a/sound/usb/pcm.c
+++ b/sound/usb/pcm.c
@@ -1095,7 +1095,7 @@ static int snd_usb_pcm_open(struct snd_p
/* need an explicit sync to catch applptr update in low-latency mode */
if (direction == SNDRV_PCM_STREAM_PLAYBACK &&
as->chip->lowlatency)
- runtime->hw.info |= SNDRV_PCM_INFO_EXPLICIT_SYNC;
+ runtime->hw.info |= SNDRV_PCM_INFO_SYNC_APPLPTR;
runtime->private_data = subs;
subs->pcm_substream = substream;
/* runtime PM is also done there */
Patches currently in stable-queue which might be from tiwai@xxxxxxx are
queue-5.15/alsa-usb-audio-rename-early_playback_start-flag-with-lowlatency_playback.patch
queue-5.15/alsa-usb-audio-disable-low-latency-playback-for-free-wheel-mode.patch
queue-5.15/alsa-usb-audio-avoid-killing-in-flight-urbs-during-draining.patch
queue-5.15/alsa-usb-audio-less-restriction-for-low-latency-playback-mode.patch
queue-5.15/alsa-usb-audio-improved-lowlatency-playback-support.patch
queue-5.15/alsa-usb-audio-check-available-frames-for-the-next-packet-size.patch
queue-5.15/alsa-usb-audio-switch-back-to-non-latency-mode-at-a-later-point.patch
queue-5.15/alsa-usb-audio-fix-packet-size-calculation-regression.patch
queue-5.15/alsa-usb-audio-don-t-start-stream-for-capture-at-prepare.patch
queue-5.15/alsa-usb-audio-disable-low-latency-mode-for-implicit-feedback-sync.patch
queue-5.15/alsa-usb-audio-add-spinlock-to-stop_urbs.patch
queue-5.15/alsa-usb-audio-restrict-rates-for-the-shared-clocks.patch
