linux/sound
Takashi Iwai 9ce650a75a ALSA: usb-audio: Reduce latency at playback start
USB-audio driver behaves a bit strangely for the playback stream --
namely, it starts sending silent packets at PCM prepare state while
the actual data is submitted at first when the trigger START is kicked
off.  This is a workaround for the behavior where URBs are processed
too quickly at the beginning.  That is, if we start submitting URBs at
trigger START, the first few URBs will be immediately completed, and
this would result in the immediate period-elapsed calls right after
the start, which may confuse applications.

OTOH, submitting the data after silent URBs would, of course, result
in a certain delay of the actual data processing, and this is rather
more serious problem on modern systems, in practice.

This patch tries to revert the workaround and lets the URB submission
starting at PCM trigger for the playback again.  As far as I've tested
with various backends (native ALSA, PA, JACK, PW), I haven't seen any
problems (famous last words :)

Note that the capture stream handling needs no such workaround, since
the capture is driven per received URB.

Link: https://lore.kernel.org/r/20210601162457.4877-6-tiwai@suse.de
Signed-off-by: Takashi Iwai <tiwai@suse.de>
2021-06-02 09:02:06 +02:00
..
ac97 ALSA: ac97: fix PM reference leak in ac97_bus_remove() 2021-05-25 08:59:08 +02:00
aoa ALSA: Convert strlcpy to strscpy when return value is unused 2021-01-08 09:30:05 +01:00
arm ARM updates for 5.12-rc1: 2021-02-22 14:27:07 -08:00
atmel
core ALSA: core: use DEVICE_ATTR_*() macro 2021-05-28 16:32:11 +02:00
drivers ALSA: drivers: opl3: fix useless self-comparison 2021-05-27 08:25:01 +02:00
firewire ALSA: firewire-motu: sequence replay for source packet header 2021-06-02 08:59:46 +02:00
hda ALSA: control - add generic LED API 2021-03-30 17:42:40 +02:00
i2c ALSA: Convert strlcpy to strscpy when return value is unused 2021-01-08 09:30:05 +01:00
isa ALSA: gus: Replace unsafe strcpy() with strscpy() 2021-05-14 09:48:33 +02:00
mips module: remove never implemented MODULE_SUPPORTED_DEVICE 2021-03-17 13:16:18 -07:00
oss sound/oss/dmasound: Remove superfluous "break" 2021-05-27 08:24:23 +02:00
parisc
pci ALSA: hda/ca0132: Make a const array static, makes object smaller 2021-05-27 08:25:54 +02:00
pcmcia module: remove never implemented MODULE_SUPPORTED_DEVICE 2021-03-17 13:16:18 -07:00
ppc ALSA: control - add generic LED API 2021-03-30 17:42:40 +02:00
sh module: remove never implemented MODULE_SUPPORTED_DEVICE 2021-03-17 13:16:18 -07:00
soc ALSA: Drop superfluous argument from snd_power_wait() 2021-05-25 08:49:39 +02:00
sparc module: remove never implemented MODULE_SUPPORTED_DEVICE 2021-03-17 13:16:18 -07:00
spi
synth
usb ALSA: usb-audio: Reduce latency at playback start 2021-06-02 09:02:06 +02:00
virtio ALSA: virtio: fix kernel-doc 2021-04-27 08:39:39 +02:00
x86 module: remove never implemented MODULE_SUPPORTED_DEVICE 2021-03-17 13:16:18 -07:00
xen module: remove never implemented MODULE_SUPPORTED_DEVICE 2021-03-17 13:16:18 -07:00
ac97_bus.c
Kconfig ALSA: virtio: add virtio sound driver 2021-03-07 09:07:16 +01:00
last.c
Makefile ALSA: virtio: add virtio sound driver 2021-03-07 09:07:16 +01:00
sound_core.c