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

[Maud Spierings <maudspierings@gocontroll.com>]

On 11/7/25 19:16, Conor Dooley wrote:
> 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?
> 

The idea is that an implementation like that will add multiple led@ 
subnodes without the led-sources property.

So devicetrees controlled by one channel will still have only one led 
with multiple sources in the devicetree.

Kind regards,
Maud

> 
>> ---
>>   .../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
>>
>>