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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
arch Handle power-gating of AMD IOMMU perf counters properly when they are used. 2021-05-09 13:00:26 -07:00
block block-5.13-2021-05-09 2021-05-09 13:25:14 -07:00
certs Kbuild updates for v5.13 (2nd) 2021-05-08 10:00:11 -07:00
crypto for-5.13/drivers-2021-04-27 2021-04-28 14:39:37 -07:00
Documentation A set of scheduler updates: 2021-05-09 13:14:34 -07:00
drivers fbmem: fix horribly incorrect placement of __maybe_unused 2021-05-09 14:03:33 -07:00
fs 3 small SMB3 chmultichannel related changesets (also for stable) 2021-05-09 13:19:29 -07:00
include Merge branch 'topic/pci-rescan-prep-v2' into for-next 2021-05-25 08:50:03 +02:00
init Merge branch 'akpm' (patches from Andrew) 2021-05-07 00:34:51 -07:00
ipc ipc/sem.c: spelling fix 2021-05-07 00:26:34 -07:00
kernel A set of scheduler updates: 2021-05-09 13:14:34 -07:00
lib Kbuild updates for v5.13 (2nd) 2021-05-08 10:00:11 -07:00
LICENSES LICENSES: Add the CC-BY-4.0 license 2020-12-08 10:33:27 -07:00
mm mm: fix typos in comments 2021-05-07 00:26:35 -07:00
net Networking fixes for 5.13-rc1, including fixes from bpf, can 2021-05-08 08:31:46 -07:00
samples Kbuild updates for v5.13 (2nd) 2021-05-08 10:00:11 -07:00
scripts Kbuild updates for v5.13 (2nd) 2021-05-08 10:00:11 -07:00
security Simple code cleanup 2021-05-05 12:08:06 -07:00
sound ALSA: usb-audio: Reduce latency at playback start 2021-06-02 09:02:06 +02:00
tools Kbuild updates for v5.13 (2nd) 2021-05-08 10:00:11 -07:00
usr .gitignore: prefix local generated files with a slash 2021-05-02 00:43:35 +09:00
virt KVM: Boost vCPU candidate in user mode which is delivering interrupt 2021-04-21 12:20:03 -04:00
.clang-format cxl for 5.12 2021-02-24 09:38:36 -08:00
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.gitattributes .gitattributes: use 'dts' diff driver for dts files 2019-12-04 19:44:11 -08:00
.gitignore .gitignore: ignore only top-level modules.builtin 2021-05-02 00:43:35 +09:00
.mailmap It's been a relatively busy cycle in docsland, though more than usually 2021-04-26 13:22:43 -07:00
COPYING COPYING: state that all contributions really are covered by this file 2020-02-10 13:32:20 -08:00
CREDITS MAINTAINERS: move Murali Karicheri to credits 2021-04-29 15:47:30 -07:00
Kbuild kbuild: rename hostprogs-y/always to hostprogs/always-y 2020-02-04 01:53:07 +09:00
Kconfig kbuild: ensure full rebuild when the compiler is updated 2020-05-12 13:28:33 +09:00
MAINTAINERS Networking fixes for 5.13-rc1, including fixes from bpf, can 2021-05-08 08:31:46 -07:00
Makefile Linux 5.13-rc1 2021-05-09 14:17:44 -07:00
README Drop all 00-INDEX files from Documentation/ 2018-09-09 15:08:58 -06:00

Linux kernel
============

There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.

In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``.  The formatted documentation can also be read online at:

    https://www.kernel.org/doc/html/latest/

There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.

Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.