Re: [PATCH v5 1/4] dt-bindings: backlight: Add max25014 support

[Conor Dooley <conor@kernel.org>]

[-- Attachment #1: Type: text/plain, Size: 4739 bytes --]

On Fri, Nov 07, 2025 at 01:49:58PM +0100, Maud Spierings via B4 Relay wrote:
> From: Maud Spierings <maudspierings@gocontroll.com>
> 
> The Maxim MAX25014 is a 4-channel automotive grade backlight driver IC
> with integrated boost controller.
> 
> Signed-off-by: Maud Spierings <maudspierings@gocontroll.com>
> 
> ---
> 
> In the current implementation the control registers for channel 1,
> control all channels. So only one led subnode with led-sources is
> supported right now. If at some point the driver functionality is
> expanded the bindings can be easily extended with it.

I'm sorry if I asked this before and forgot or w/e, but how backwards
compatible is this? If they control all channels and it gets changed to
only control channel one, how will a changed kernel understand the
difference between a new devicetree that only wants to control channel 1
and an old devicetree that is trying to use channel 1 to control all
channels?

Cheers,
Conor.

> ---
>  .../bindings/leds/backlight/maxim,max25014.yaml    | 107 +++++++++++++++++++++
>  MAINTAINERS                                        |   5 +
>  2 files changed, 112 insertions(+)
> 
> diff --git a/Documentation/devicetree/bindings/leds/backlight/maxim,max25014.yaml b/Documentation/devicetree/bindings/leds/backlight/maxim,max25014.yaml
> new file mode 100644
> index 000000000000..e83723224b07
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/leds/backlight/maxim,max25014.yaml
> @@ -0,0 +1,107 @@
> +# SPDX-License-Identifier: (GPL-2.0 OR BSD-2-Clause)
> +%YAML 1.2
> +---
> +$id: http://devicetree.org/schemas/leds/backlight/maxim,max25014.yaml#
> +$schema: http://devicetree.org/meta-schemas/core.yaml#
> +
> +title: Maxim max25014 backlight controller
> +
> +maintainers:
> +  - Maud Spierings <maudspierings@gocontroll.com>
> +
> +properties:
> +  compatible:
> +    enum:
> +      - maxim,max25014
> +
> +  reg:
> +    maxItems: 1
> +
> +  "#address-cells":
> +    const: 1
> +
> +  "#size-cells":
> +    const: 0
> +
> +  enable-gpios:
> +    maxItems: 1
> +
> +  interrupts:
> +    maxItems: 1
> +
> +  power-supply:
> +    description: Regulator which controls the boost converter input rail.
> +
> +  pwms:
> +    maxItems: 1
> +
> +  maxim,iset:
> +    $ref: /schemas/types.yaml#/definitions/uint32
> +    maximum: 15
> +    default: 11
> +    description:
> +      Value of the ISET field in the ISET register. This controls the current
> +      scale of the outputs, a higher number means more current.
> +
> +  led@0:
> +    type: object
> +    description: Properties for a string of connected LEDs.
> +    $ref: common.yaml#
> +
> +    properties:
> +      reg:
> +        const: 0
> +
> +      led-sources:
> +        allOf:
> +          - minItems: 1
> +            maxItems: 4
> +            items:
> +              minimum: 0
> +              maximum: 3
> +            default: [0, 1, 2, 3]
> +
> +      default-brightness:
> +        minimum: 0
> +        maximum: 100
> +        default: 50
> +
> +    required:
> +      - reg
> +
> +    additionalProperties: false
> +
> +required:
> +  - compatible
> +  - reg
> +
> +additionalProperties: false
> +
> +examples:
> +  - |
> +    #include <dt-bindings/gpio/gpio.h>
> +    #include <dt-bindings/interrupt-controller/irq.h>
> +
> +    i2c {
> +        #address-cells = <1>;
> +        #size-cells = <0>;
> +
> +        backlight@6f {
> +            compatible = "maxim,max25014";
> +            reg = <0x6f>;
> +            #address-cells = <1>;
> +            #size-cells = <0>;
> +            enable-gpios = <&gpio1 4 GPIO_ACTIVE_HIGH>;
> +            interrupt-parent = <&gpio1>;
> +            interrupts = <2 IRQ_TYPE_EDGE_FALLING>;
> +            power-supply = <&reg_backlight>;
> +            pwms = <&pwm1>;
> +            maxim,iset = <7>;
> +
> +            led@0 {
> +                reg = <0>;
> +                led-sources = <0 1 2 3>;
> +                default-brightness = <50>;
> +            };
> +        };
> +    };
> diff --git a/MAINTAINERS b/MAINTAINERS
> index 58c7e3f678d8..606ce086f758 100644
> --- a/MAINTAINERS
> +++ b/MAINTAINERS
> @@ -15261,6 +15261,11 @@ F:	Documentation/userspace-api/media/drivers/max2175.rst
>  F:	drivers/media/i2c/max2175*
>  F:	include/uapi/linux/max2175.h
>  
> +MAX25014 BACKLIGHT DRIVER
> +M:	Maud Spierings <maudspierings@gocontroll.com>
> +S:	Maintained
> +F:	Documentation/devicetree/bindings/leds/backlight/maxim,max25014.yaml
> +
>  MAX31335 RTC DRIVER
>  M:	Antoniu Miclaus <antoniu.miclaus@analog.com>
>  L:	linux-rtc@vger.kernel.org
> 
> -- 
> 2.51.2
> 
> 

[-- Attachment #2: signature.asc --]
[-- Type: application/pgp-signature, Size: 228 bytes --]