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30000d80b5
linux/drivers/video/backlight
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Enric Balletbo i Serra 88ba95bedb backlight: pwm_bl: Compute brightness of LED linearly to human eye 
When you want to change the brightness using a PWM signal, one thing you
need to consider is how human perceive the brightness. Human perceive
the brightness change non-linearly, we have better sensitivity at low
luminance than high luminance, so to achieve perceived linear dimming,
the brightness must be matches to the way our eyes behave. The CIE 1931
lightness formula is what actually describes how we perceive light.

This patch computes a default table with the brightness levels filled
with the numbers provided by the CIE 1931 algorithm, the number of the
brightness levels is calculated based on the PWM resolution.

The calculation of the table using the CIE 1931 algorithm is enabled by
default when you do not define the 'brightness-levels' propriety in your
device tree.

Signed-off-by: Enric Balletbo i Serra <enric.balletbo@collabora.com>
Acked-by: Daniel Thompson <daniel.thompson@linaro.org>
Signed-off-by: Lee Jones <lee.jones@linaro.org>
2018-07-04 10:31:18 +01:00
..
88pm860x_bl.c backlight: 88pm860x_bl: Add missing of_node_put 2015-10-15 12:06:21 +01:00
aat2870_bl.c backlight: Remove .owner field for drivers using module_platform_driver 2014-08-28 14:09:48 +01:00
adp5520_bl.c backlight: adp5520: Fix error handling in adp5520_bl_probe() 2017-01-04 11:37:31 +00:00
adp8860_bl.c treewide: devm_kzalloc() -> devm_kcalloc() 2018-06-12 16:19:22 -07:00
adp8870_bl.c treewide: devm_kzalloc() -> devm_kcalloc() 2018-06-12 16:19:22 -07:00
ams369fg06.c spi: Drop owner assignment from spi_drivers 2015-10-28 10:30:17 +09:00
apple_bl.c backlight: apple_bl: Deprecate pci_get_bus_and_slot() 2017-12-20 13:47:05 +00:00
arcxcnn_bl.c backlight: Add support for Arctic Sand LED backlight driver chips 2017-04-25 09:22:23 +01:00
as3711_bl.c backlight: as3711_bl: Fix Device Tree node leaks 2018-06-11 13:40:45 +01:00
backlight.c video: backlight: Add devres versions of of_find_backlight 2018-01-29 10:34:53 -05:00
bd6107.c backlight: Remove trivial get_brightness implementations 2014-06-23 13:24:22 +01:00
corgi_lcd.c backlight: tdo24m: Fix the SPI CS between transfers 2018-01-08 09:21:57 +00:00
cr_bllcd.c backlight: cr_bllcd: Add blank line after declarations 2014-08-29 08:24:51 +01:00
da903x_bl.c backlight: Remove .owner field for drivers using module_platform_driver 2014-08-28 14:09:48 +01:00
da9052_bl.c backlight: da9052: Fix module autoload 2017-01-04 11:37:58 +00:00
ep93xx_bl.c backlight: Remove .owner field for drivers using module_platform_driver 2014-08-28 14:09:48 +01:00
generic_bl.c backlight: generic-bl: Remove DRIVER1 state 2018-04-30 13:25:14 +01:00
gpio_backlight.c backlight: gpio_backlight: Delete pdata inversion 2017-08-07 17:11:28 +01:00
hp680_bl.c
hx8357.c
ili922x.c backlight: ili922x: Remove redundant variable len 2017-11-08 10:43:49 +00:00
ili9320.c
ili9320.h
ipaq_micro_bl.c backlight: ipaq_micro: Fix sparse non static symbol warning 2014-07-31 10:31:22 +01:00
jornada720_bl.c backlight: jornada720: Remove 'else' after a return 2014-08-29 08:26:32 +01:00
jornada720_lcd.c backlight: jornada720: Remove 'else' after a return 2014-08-29 08:26:51 +01:00
kb3886_bl.c dmi: Mark all struct dmi_system_id instances const 2017-09-14 11:59:30 +02:00
Kconfig backlight: otm3225a: Add support for ORISE OTM3225A LCD SoC 2018-04-30 10:50:44 +01:00
l4f00242t03.c spi: Drop owner assignment from spi_drivers 2015-10-28 10:30:17 +09:00
lcd.c backlight: lcd: Fix race condition during register 2017-01-04 11:37:31 +00:00
ld9040_gamma.h
ld9040.c spi: Drop owner assignment from spi_drivers 2015-10-28 10:30:17 +09:00
lm3533_bl.c backlight: Remove .owner field for drivers using module_platform_driver 2014-08-28 14:09:48 +01:00
lm3630a_bl.c backlight: lm3630a: Bump REG_MAX value to 0x50 instead of 0x1F 2017-07-17 13:27:06 +01:00
lm3639_bl.c backlight: lm3639: Remove unnecessary return statements 2014-08-29 08:25:23 +01:00
lms283gf05.c spi: Drop owner assignment from spi_drivers 2015-10-28 10:30:17 +09:00
lms501kf03.c spi: Drop owner assignment from spi_drivers 2015-10-28 10:30:17 +09:00
locomolcd.c
lp855x_bl.c treewide: devm_kzalloc() -> devm_kcalloc() 2018-06-12 16:19:22 -07:00
lp8788_bl.c backlight: lp8788: Explicitly apply PWM config extracted from pwm_args 2016-05-17 14:45:04 +02:00
ltv350qv.c spi: Drop owner assignment from spi_drivers 2015-10-28 10:30:17 +09:00
ltv350qv.h
lv5207lp.c backlight: Remove trivial get_brightness implementations 2014-06-23 13:24:22 +01:00
Makefile backlight: otm3225a: Add support for ORISE OTM3225A LCD SoC 2018-04-30 10:50:44 +01:00
max8925_bl.c backlight: max8925_bl: Fix Device Tree node lookup 2018-06-11 13:40:32 +01:00
omap1_bl.c backlight: omap1: add blank line after declarations 2014-08-29 08:27:53 +01:00
ot200_bl.c backlight: Remove .owner field for drivers using module_platform_driver 2014-08-28 14:09:48 +01:00
otm3225a.c backlight: otm3225a: Add support for ORISE OTM3225A LCD SoC 2018-04-30 10:50:44 +01:00
pandora_bl.c backlight: pandora: Stop using BL_CORE_DRIVER1 2018-04-30 13:25:14 +01:00
pcf50633-backlight.c backlight: pcf50633: Add blank line after declarations 2014-08-29 08:25:53 +01:00
platform_lcd.c backlight: Remove .owner field for drivers using module_platform_driver 2014-08-28 14:09:48 +01:00
pm8941-wled.c backlight: pm8941-wled: Add default-brightness property 2015-10-30 18:47:51 +00:00
pwm_bl.c backlight: pwm_bl: Compute brightness of LED linearly to human eye 2018-07-04 10:31:18 +01:00
rave-sp-backlight.c backlight: Add RAVE SP backlight driver 2018-04-30 10:50:43 +01:00
s6e63m0_gamma.h
s6e63m0.c spi: Drop owner assignment from spi_drivers 2015-10-28 10:30:17 +09:00
sky81452-backlight.c backlight: sky81452: Remove unneeded use of IS_ERR_VALUE() macro 2015-08-25 08:43:21 +01:00
tdo24m.c backlight: tdo24m: Fix the SPI CS between transfers 2018-01-08 09:21:57 +00:00
tosa_bl.c backlight-tosa: Delete unnecessary assignment for the field "owner" 2016-10-06 09:27:25 +01:00
tosa_lcd.c backlight: tdo24m: Fix the SPI CS between transfers 2018-01-08 09:21:57 +00:00
tps65217_bl.c backlight: tps65217_bl: Fix Device Tree node lookup 2018-06-11 13:40:39 +01:00
vgg2432a4.c spi: Drop owner assignment from spi_drivers 2015-10-28 10:30:17 +09:00
wm831x_bl.c backlight: wm831x_bl: Add blank line after declarations 2014-08-29 08:26:21 +01:00