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Both adp8860 and adp8870 define some extensions to the backlight class. This causes warnings: Warning: /sys/class/backlight/<backlight>/ambient_light_level is defined 2 times: /sys/class/backlight/<backlight>/ambient_light_level:8 /sys/class/backlight/<backlight>/ambient_light_level:30 Warning: /sys/class/backlight/<backlight>/ambient_light_zone is defined 2 times: /sys/class/backlight/<backlight>/ambient_light_zone:18 /sys/class/backlight/<backlight>/ambient_light_zone:40 As ABI definitions shouldn't be duplicated. Unfortunately, the ABI is dependent on the specific device features. As such, ambient_light_level range is somewhat different among the supported devices. The ambient_light_zone is even worse: the meanings of each preset are different, and there's no ABI to retrieve the supported types nor their meanins. Unfortunately, it is too late to fix it without causing regressions, as this has been used since Kernel v2.6.35. Rewrite those ABI documentation using the current documentation as a reference, and double-checking at the datasheets: https://www.analog.com/media/en/technical-documentation/data-sheets/ADP8870.pdf https://www.analog.com/media/en/technical-documentation/data-sheets/ADP8860.pdf in order to properly document the differences between those two drivers. Acked-by: Jonathan Corbet <corbet@lwn.net> Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org> Link: https://lore.kernel.org/r/342195ad5a819d9bcfcebc133c77ab69b4211672.1604042072.git.mchehab+huawei@kernel.org Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
86 lines
2.3 KiB
Text
86 lines
2.3 KiB
Text
What: /sys/class/backlight/<backlight>/scale
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Date: July 2019
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KernelVersion: 5.4
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Contact: Daniel Thompson <daniel.thompson@linaro.org>
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Description:
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Description of the scale of the brightness curve.
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The human eye senses brightness approximately logarithmically,
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hence linear changes in brightness are perceived as being
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non-linear. To achieve a linear perception of brightness changes
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controls like sliders need to apply a logarithmic mapping for
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backlights with a linear brightness curve.
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Possible values of the attribute are:
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unknown
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The scale of the brightness curve is unknown.
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linear
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The brightness changes linearly with each step. Brightness
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controls should apply a logarithmic mapping for a linear
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perception.
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non-linear
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The brightness changes non-linearly with each step. Brightness
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controls should use a linear mapping for a linear perception.
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What: /sys/class/backlight/<backlight>/ambient_light_level
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Date: Apr, 2010
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KernelVersion: v2.6.35
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Contact: Michael Hennerich <michael.hennerich@analog.com>
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Description:
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(RO) Get conversion value of the light sensor.
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The value is automatically updated every 80 ms when the
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light sensor is enabled.
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The value range is device-driver specific:
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For ADP8870:
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It returns integer between 0 (dark) and 8000 (max ambient
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brightness).
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For ADP8860:
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It returns a 13-bits integer.
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What: /sys/class/backlight/<backlight>/ambient_light_zone
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Date: Apr, 2010
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KernelVersion: v2.6.35
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Contact: Michael Hennerich <michael.hennerich@analog.com>,
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device-drivers-devel@blackfin.uclinux.org
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Description:
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(RW) Read or write the specific brightness level at which the
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backlight operates.
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The value meaning is device-driver specific:
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For ADP8860:
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== ==========================
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0 Off: Backlight set to 0 mA
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1 Level 1: daylight
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2 Level 2: bright
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3 Level 3: dark
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== ==========================
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For ADP8870:
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== ==========================
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0 Off: Backlight set to 0 mA
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1 Level 1: daylight
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2 Level 2: bright
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3 Level 3: office
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4 Level 4: indoor
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5 Level 5: dark
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== ==========================
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Writing 0 returns to normal/automatic ambient light level
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operation.
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It can be enabled by writing the value stored in
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/sys/class/backlight/<backlight>/max_brightness to
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/sys/class/backlight/<backlight>/brightness.
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