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OpenCloudOS-Kernel
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Matthias Kaehlcke 73fbfc4994 backlight: pwm_bl: Fix heuristic to determine number of brightness levels 
With commit 88ba95bedb ("backlight: pwm_bl: Compute brightness of
LED linearly to human eye") the number of set bits (aka hweight())
in the PWM period is used in the heuristic to determine the number
of brightness levels, when the brightness table isn't specified in
the DT. The number of set bits doesn't provide a reliable clue about
the length of the period, instead change the heuristic to:

 nlevels = period / fls(period)

Also limit the maximum number of brightness levels to 4096 to avoid
excessively large tables.

With this the number of levels increases monotonically with the PWM
period, until the maximum of 4096 levels is reached:

period (ns)    # levels

100    	       16
500	       62
1000	       111
5000	       416
10000	       769
50000	       3333
100000	       4096

Fixes: 88ba95bedb ("backlight: pwm_bl: Compute brightness of LED linearly to human eye")
Signed-off-by: Matthias Kaehlcke <mka@chromium.org>
Acked-by: Daniel Thompson <daniel.thompson@linaro.org>
Tested-by: Enric Balletbo i Serra <enric.balletbo@collabora.com>
Signed-off-by: Lee Jones <lee.jones@linaro.org>
 		2019-06-27 07:09:05 +01:00
Documentation Merge branch 'akpm' (patches from Andrew) 2019-05-19 12:15:32 -07:00
LICENSES LICENSES: Rename other to deprecated 2019-05-03 06:34:32 -06:00
arch Merge branch 'akpm' (patches from Andrew) 2019-05-19 12:15:32 -07:00
block for-5.2/block-post-20190516 2019-05-16 19:08:15 -07:00
certs kexec, KEYS: Make use of platform keyring for signature verify 2019-02-04 17:34:07 -05:00
crypto Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net-next 2019-05-07 22:03:58 -07:00
drivers backlight: pwm_bl: Fix heuristic to determine number of brightness levels 2019-06-27 07:09:05 +01:00
fs This pull request contains the following fixes for UBIFS: 2019-05-19 15:22:03 -07:00
include Merge branch 'akpm' (patches from Andrew) 2019-05-19 12:15:32 -07:00
init initramfs: don't free a non-existent initrd 2019-05-18 15:52:26 -07:00
ipc ipc: do cyclic id allocation for the ipc object. 2019-05-14 19:52:52 -07:00
kernel Merge branch 'akpm' (patches from Andrew) 2019-05-19 12:15:32 -07:00
lib slab: remove /proc/slab_allocators 2019-05-16 15:51:55 -07:00
mm Merge branch 'akpm' (patches from Andrew) 2019-05-19 12:15:32 -07:00
net treewide: prefix header search paths with $(srctree)/ 2019-05-18 11:49:57 +09:00
samples samples: guard sub-directories with CONFIG options 2019-05-18 11:29:01 +09:00
scripts kconfig: use 'else ifneq' for Makefile to improve readability 2019-05-19 09:34:35 +09:00
security Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net 2019-05-13 15:15:00 -07:00
sound sound fixes for 5.2-rc1 2019-05-17 13:57:54 -07:00
tools Merge branch 'perf-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2019-05-19 11:20:22 -07:00
usr user/Makefile: Fix typo and capitalization in comment section 2018-12-11 00:18:03 +09:00
virt * ARM: support for SVE and Pointer Authentication in guests, PMU improvements 2019-05-17 10:33:30 -07:00
.clang-format Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net 2019-04-17 11:26:25 -07:00
.cocciconfig
…
.get_maintainer.ignore Opt out of scripts/get_maintainer.pl 2019-05-16 10:53:40 -07:00
.gitattributes .gitattributes: set git diff driver for C source code files 2016-10-07 18:46:30 -07:00
.gitignore .gitignore: exclude .get_maintainer.ignore and .gitattributes 2019-05-18 11:49:54 +09:00
.mailmap A reasonably busy cycle for docs, including: 2019-05-08 12:42:50 -07:00
COPYING COPYING: use the new text with points to the license files 2018-03-23 12:41:45 -06:00
CREDITS Char/Misc driver patches for 5.1-rc1 2019-03-06 14:18:59 -08:00
Kbuild Kbuild updates for v5.1 2019-03-10 17:48:21 -07:00
Kconfig kconfig: move the "Executable file formats" menu to fs/Kconfig.binfmt 2018-08-02 08:06:55 +09:00
MAINTAINERS Kbuild updates for v5.2 (2nd) 2019-05-19 11:53:58 -07:00
Makefile Linux 5.2-rc1 2019-05-19 15:47:09 -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.