From: Takashi Iwai <tiwai@suse.de>
To: alsa-devel@alsa-project.org
Subject: [PATCH] ALSA: usb-audio: Less restriction for low-latency playback mode
Date: Mon, 11 Oct 2021 12:36:50 +0200 [thread overview]
Message-ID: <20211011103650.10182-1-tiwai@suse.de> (raw)
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")
Signed-off-by: Takashi Iwai <tiwai@suse.de>
---
sound/usb/pcm.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/sound/usb/pcm.c b/sound/usb/pcm.c
index 3bb095a3c9b6..95ec8eec1bb0 100644
--- a/sound/usb/pcm.c
+++ b/sound/usb/pcm.c
@@ -1102,7 +1102,7 @@ static int snd_usb_pcm_open(struct snd_pcm_substream *substream)
/* 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 */
--
2.31.1
reply other threads:[~2021-10-11 10:37 UTC|newest]
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