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Thomas Gleixner f2ff7147c6 ALSA: pcsp: Make hrtimer forwarding more robust
The hrtimer callback pcsp_do_timer() prepares rearming of the timer with
hrtimer_forward(). hrtimer_forward() is intended to provide a mechanism to
forward the expiry time of the hrtimer by a multiple of the period argument
so that the expiry time greater than the time provided in the 'now'
argument.

pcsp_do_timer() invokes hrtimer_forward() with the current timer expiry
time as 'now' argument. That's providing a periodic timer expiry, but is
not really robust when the timer callback is delayed so that the resulting
new expiry time is already in the past which causes the callback to be
invoked immediately again. If the timer is delayed then the back to back
invocation is not really making it better than skipping the missed
periods. Sound is distorted in any case.

Use hrtimer_forward_now() which ensures that the next expiry is in the
future. This prevents hogging the CPU in the timer expiry code and allows
later on to remove hrtimer_forward() from the public interfaces.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: alsa-devel@alsa-project.org
Cc: Takashi Iwai <tiwai@suse.com>
Cc: Jaroslav Kysela <perex@perex.cz>
Link: https://lore.kernel.org/r/20210923153339.623208460@linutronix.de
Signed-off-by: Takashi Iwai <tiwai@suse.de>
2021-09-28 10:58:08 +02:00
Documentation An assortment of improvements for auxdisplay: 2021-09-12 16:00:49 -07:00
LICENSES LICENSES/dual/CC-BY-4.0: Git rid of "smart quotes" 2021-07-15 06:31:24 -06:00
arch Updates for the SMP and CPU hotplug: 2021-09-12 12:42:51 -07:00
block block-5.15-2021-09-11 2021-09-11 10:19:51 -07:00
certs certs: Add support for using elliptic curve keys for signing modules 2021-08-23 19:55:42 +03:00
crypto Merge branch 'linus' of git://git.kernel.org/pub/scm/linux/kernel/git/herbert/crypto-2.6 2021-08-30 12:57:10 -07:00
drivers An assortment of improvements for auxdisplay: 2021-09-12 16:00:49 -07:00
fs Merge branch 'misc.namei' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2021-09-12 10:43:51 -07:00
include ALSA: rawmidi: introduce SNDRV_RAWMIDI_IOCTL_USER_PVERSION 2021-09-23 09:26:40 +02:00
init More tracing updates for 5.15: 2021-09-09 13:11:15 -07:00
ipc ARM development updates for 5.15: 2021-09-09 13:25:49 -07:00
kernel - Make sure the idle timer expires in hardirq context, on PREEMPT_RT 2021-09-12 11:37:41 -07:00
lib Minor fixes to the processing of the bootconfig tree. 2021-09-11 10:16:30 -07:00
mm ARM development updates for 5.15: 2021-09-09 13:25:49 -07:00
net virtio,vdpa,vhost: features, fixes 2021-09-11 14:48:42 -07:00
samples kgdb patches for 5.15 2021-09-07 12:08:04 -07:00
scripts RISC-V Patches for the 5.15 Merge Window, Part 2 2021-09-11 14:29:42 -07:00
security Kbuild updates for v5.15 2021-09-03 15:33:47 -07:00
sound ALSA: pcsp: Make hrtimer forwarding more robust 2021-09-28 10:58:08 +02:00
tools perf tools changes for v5.15: 2nd batch 2021-09-12 16:18:15 -07:00
usr .gitignore: prefix local generated files with a slash 2021-05-02 00:43:35 +09:00
virt KVM: Drop unused kvm_dirty_gfn_invalid() 2021-09-06 08:23:46 -04:00
.clang-format clang-format: Update with the latest for_each macro list 2021-05-12 23:32:39 +02:00
.cocciconfig scripts: add Linux .cocciconfig for coccinelle 2016-07-22 12:13:39 +02:00
.get_maintainer.ignore Opt out of scripts/get_maintainer.pl 2019-05-16 10:53:40 -07:00
.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 mailmap: update email address of Matthias Fuchs and Thomas Körper 2021-08-19 09:39:44 +02:00
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 ASoC: Fixes for v5.15 2021-09-21 18:42:14 +02:00
Makefile Linux 5.15-rc1 2021-09-12 16:28:37 -07:00
README Drop all 00-INDEX files from Documentation/ 2018-09-09 15:08:58 -06:00

README

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.