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

Maud Spierings
2025-11-10T07:55:24Z

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
>>
>>