Re: [PATCH v2] pwm_backlight: Add device tree support for Low ThresholdBrightness

[Stephen Warren]

On 09/20/2012 10:51 PM, Philip, Avinash wrote:
> Some backlights perform poorly when driven by a PWM with a short
> duty-cycle. For such devices, the low threshold can be used to specify a
> lower bound for the duty-cycle and should be chosen to exclude the
> problematic range.
> 
> This patch adds support for an optional low-threshold-brightness
> property.

> diff --git a/Documentation/devicetree/bindings/video/backlight/pwm-backlight.txt b/Documentation/devicetree/bindings/video/backlight/pwm-backlight.txt

>  Optional properties:
>    - pwm-names: a list of names for the PWM devices specified in the
>                 "pwms" property (see PWM binding[0])
> +  - low-threshold-brightness: brightness threshold low level. Low threshold
> +    brightness set to value so that backlight present on low end of
> +    brightness.

For my education, why not just specify values above this value in the
brightness-levels array; how do those two interact? It seems like any
description of that is missing from the PWM documentation, and would be
good to have in the DT binding too.

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