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SubjectRe: [PATCH v2 2/3] dt-bindings: backlight: add lm3630a bindings
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Hello

On 4/1/19 5:30 AM, Brian Masney wrote:
> Add new backlight bindings for the TI LM3630A dual-string white LED.
>
> Signed-off-by: Brian Masney <masneyb@onstation.org>
> ---
> .../leds/backlight/lm3630a-backlight.yaml | 112 ++++++++++++++++++
> 1 file changed, 112 insertions(+)
> create mode 100644 Documentation/devicetree/bindings/leds/backlight/lm3630a-backlight.yaml
>
> diff --git a/Documentation/devicetree/bindings/leds/backlight/lm3630a-backlight.yaml b/Documentation/devicetree/bindings/leds/backlight/lm3630a-backlight.yaml
> new file mode 100644
> index 000000000000..42a8c59d237a
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/leds/backlight/lm3630a-backlight.yaml
> @@ -0,0 +1,112 @@
> +# SPDX-License-Identifier: (GPL-2.0 OR BSD-2-Clause)
> +%YAML 1.2
> +---
> +$id: http://devicetree.org/schemas/leds/backlight/lm3630a-backlight.yaml#
> +$schema: http://devicetree.org/meta-schemas/core.yaml#
> +
> +title: TI LM3630A High-Efficiency Dual-String White LED
> +
> +maintainers:
> + - Lee Jones <lee.jones@linaro.org>
> + - Daniel Thompson <daniel.thompson@linaro.org>
> + - Jingoo Han <jingoohan1@gmail.com>
> +
> +description: |
> + The LM3630A is a current-mode boost converter which supplies the power and
> + controls the current in up to two strings of 10 LEDs per string.
> + https://www.ti.com/product/LM3630A
> +
> +properties:
> + compatible:
> + const: ti,lm3630a
> +
> + reg:
> + maxItems: 1
> +

No description on the reg here. Assumed to be the i2c address?

> + ti,linear-mapping-mode:
> + description: |
> + Enable linear mapping mode. If disabled, then it will use exponential
> + mapping mode in which the ramp up/down appears to have a more uniform
> + tranisiton to the human eye.

s/tranisiton/transition

> + type: boolean
> +
> +required:
> + - compatible
> + - reg
> +
> +patternProperties:
> + "^led*$":
> + type: object
> + description: |
> + Properties for a string of connected LEDs.
> +

I have written a few of these drivers that have control bank support to control. We have
been defining the reg property as the control bank id

reg 0 - Control bank A
reg 1 - Control bank B

Then use the led-sources to define what outputs are associated with which control bank.

This way the hardware can just have CB B enabled without CB A.

something like below would allow just control bank B to be enabled.

led@1 {
reg = <1>;
label = "main-lcd";
default-brightness = <200>;
max-brightness = <255>;
};

This would connect control bank B to control bank A. Or just use a flag to denote to connect them
and not use led-sources. But led-sources is the property of choice.

led@0 {
reg = <0>;
led-sources = < 0 1 >;
label = "main-lcd";
default-brightness = <200>;
max-brightness = <255>;
};

And just the presence of 2 child nodes would indicate individual bank control
led@0 {
reg = <0>;
label = "main-lcd";
default-brightness = <200>;
max-brightness = <255>;
};

led@1 {
reg = <1>;
label = "main-keypad";
default-brightness = <200>;
max-brightness = <255>;
};

> + properties:
> + label:
> + description: |
> + The label for this LED. If omitted, the label is taken from the node
> + name (excluding the unit address). It has to uniquely identify a
> + device, i.e. no other LED class device can be assigned the same label.
> +
> + led-sources:
> + description: |
> + List of device current outputs the LED is connected to.
> + allOf:
> + - $ref: /schemas/types.yaml#/definitions/uint32-array
> + - minItems: 1
> + maxItems: 2
> + items:
> + minimum: 0
> + maximum: 1
> +

label and led-sources are already defined in the common.txt no need to redefine them here.

> + default-brightness:
> + description: Default brightness level on boot.
> + minimum: 0
> + maximum: 255
> +
> + max-brightness:
> + description: Maximum brightness level on boot.

This is not the max brightness on boot. This is the max brightness that is allowed during runtime.

Dan

> + minimum: 0
> + maximum: 255
> +
> +examples:
> + - |
> + i2c {
> + #address-cells = <1>;
> + #size-cells = <0>;
> +
> + lm3630a_bl@38 {
> + compatible = "ti,lm3630a";
> + status = "ok";
> + reg = <0x38>;
> +
> + led {
> + label = "main-lcd";
> + led-sources = <0 1>;
> + default-brightness = <200>;
> + max-brightness = <255>;
> + };
> + };
> + };
> + - |
> + i2c {
> + #address-cells = <1>;
> + #size-cells = <0>;
> +
> + lm3630a_bl@38 {
> + compatible = "ti,lm3630a";
> + status = "ok";
> + reg = <0x38>;
> +
> + led-bank-a {
> + led-sources = <0>;
> + default-brightness = <150>;
> + ti,linear-mapping-mode;
> + };
> +
> + led-bank-b {
> + led-sources = <1>;
> + default-brightness = <225>;
> + ti,linear-mapping-mode;
> + };
> + };
> + };
>


--
------------------
Dan Murphy

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