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authorLinus Torvalds <torvalds@linux-foundation.org>2019-09-23 19:33:56 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2019-09-23 19:33:56 -0700
commitd0b3cfee333eb7eecb6ce72f06f5a02d249b9bdf (patch)
treebd884989b8e0d08a64cb40384819a6e670ccf470 /Documentation
parent299d14d4c31aff3b37a03894e012edf8421676ee (diff)
parentc0b64faf0fe6ca2574a00faed1ae833130db4e08 (diff)
downloadlinux-d0b3cfee333eb7eecb6ce72f06f5a02d249b9bdf.tar.bz2
Merge tag 'backlight-next-5.4' of git://git.kernel.org/pub/scm/linux/kernel/git/lee/backlight
Pull backlight updates from Lee Jones: "Core Frameworks - Obtain scale type through sysfs New Functionality: - Provide Device Tree functionality in rave-sp-backlight - Calculate if scale type is (non-)linear in pwm_bl Fix-ups: - Simplify code in lm3630a_bl - Trivial rename/whitespace/typo fixes in lms283gf05 - Remove superfluous NULL check in tosa_lcd - Fix power state initialisation in gpio_backlight - List supported file in MAINTAINERS Bug Fixes: - Kconfig - default to not building unless requested in {LED,BACKLIGHT}_CLASS_DEVICE" * tag 'backlight-next-5.4' of git://git.kernel.org/pub/scm/linux/kernel/git/lee/backlight: backlight: pwm_bl: Set scale type for brightness curves specified in the DT backlight: pwm_bl: Set scale type for CIE 1931 curves backlight: Expose brightness curve type through sysfs MAINTAINERS: Add entry for stable backlight sysfs ABI documentation backlight: gpio-backlight: Correct initial power state handling video: backlight: tosa_lcd: drop check because i2c_unregister_device() is NULL safe video: backlight: Drop default m for {LCD,BACKLIGHT_CLASS_DEVICE} backlight: lms283gf05: Fix a typo in the description passed to 'devm_gpio_request_one()' backlight: lm3630a: Switch to use fwnode_property_count_uXX() backlight: rave-sp: Leave initial state and register with correct device
Diffstat (limited to 'Documentation')
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+What: /sys/class/backlight/<backlight>/scale
+Date: July 2019
+KernelVersion: 5.4
+Contact: Daniel Thompson <daniel.thompson@linaro.org>
+Description:
+ Description of the scale of the brightness curve.
+
+ The human eye senses brightness approximately logarithmically,
+ hence linear changes in brightness are perceived as being
+ non-linear. To achieve a linear perception of brightness changes
+ controls like sliders need to apply a logarithmic mapping for
+ backlights with a linear brightness curve.
+
+ Possible values of the attribute are:
+
+ unknown
+ The scale of the brightness curve is unknown.
+
+ linear
+ The brightness changes linearly with each step. Brightness
+ controls should apply a logarithmic mapping for a linear
+ perception.
+
+ non-linear
+ The brightness changes non-linearly with each step. Brightness
+ controls should use a linear mapping for a linear perception.