Re: [PATCH 3/3] devicetree: Add led-backlight binding

[Tomi Valkeinen <tomi.valkeinen@ti.com>]

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On 25/08/15 16:39, Jacek Anaszewski wrote:

>> +Example:
>> +
>> +    backlight {
>> +        compatible = "led-backlight";
>> +        leds = <&backlight_led>;
>> +
>> +        brightness-levels = <0 4 8 16 32 64 128 255>;
> 
> brightness level is not a suitable unit for describing LED brightness
> in a Device Tree, as it is not a physical unit. We have led-max-microamp
> property for this, expressed in microamperes, please refer to [0] from
> linux-next.

Hmm, ok, but what should the driver do with microamperes? As far as I
see, "enum led_brightness" (which is between 0-255) is used to set the
brightness to LEDs. I don't see any function accepting microamperes.

>> +        default-brightness-level = <6>;
> 
> This also should be microamperes.

This is an index to the above brightness-levels array. It's not LED
brightness, but backlight brightness, between 0 and
ARRAY_SIZE(brightness-levels) - 1.

 Tomi


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