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dt-bindings: pwm-backlight: Move brightness-levels to optional 

The patch 'backlight: pwm_bl: compute brightness of LED linearly to
human eye' introduced a default brightness-levels table that is used
when brightness-levels is not available in the dts. So move
brightness-levels and default-brightness-level to be optional.

Signed-off-by: Enric Balletbo i Serra <enric.balletbo@collabora.com>
Reviewed-by: Rob Herring <robh@kernel.org>
Acked-by: Daniel Thompson <daniel.thompson@linaro.org>
Signed-off-by: Lee Jones <lee.jones@linaro.org>
This commit is contained in:
Enric Balletbo i Serra 2018-04-09 10:33:33 +02:00 committed by Lee Jones
parent 88ba95bedb
commit c8cc0f0460
1 changed files with 8 additions and 7 deletions
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15
Documentation/devicetree/bindings/leds/backlight/pwm-backlight.txt
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@ -3,13 +3,6 @@ pwm-backlight bindings
Required properties:
- compatible: "pwm-backlight"
- pwms: OF device-tree PWM specification (see PWM binding[0])
- brightness-levels: Array of distinct brightness levels. Typically these
are in the range from 0 to 255, but any range starting at 0 will do.
The actual brightness level (PWM duty cycle) will be interpolated
from these values. 0 means a 0% duty cycle (darkest/off), while the
last value in the array represents a 100% duty cycle (brightest).
- default-brightness-level: the default brightness level (index into the
array defined by the "brightness-levels" property)
- power-supply: regulator for supply voltage
Optional properties:
@ -21,6 +14,14 @@ Optional properties:
and enabling the backlight using GPIO.
- pwm-off-delay-ms: Delay in ms between disabling the backlight using GPIO
and setting PWM value to 0.
- brightness-levels: Array of distinct brightness levels. Typically these
are in the range from 0 to 255, but any range starting at
0 will do. The actual brightness level (PWM duty cycle)
will be interpolated from these values. 0 means a 0% duty
cycle (darkest/off), while the last value in the array
represents a 100% duty cycle (brightest).
- default-brightness-level: The default brightness level (index into the
array defined by the "brightness-levels" property).
- num-interpolated-steps: Number of interpolated steps between each value
of brightness-levels table. This way a high
resolution pwm duty cycle can be used without