On Thu, Oct 09, 2025 at 10:55:42AM -0400, Frank Li wrote: > On Thu, Oct 09, 2025 at 08:48:25AM +0200, Maud Spierings via B4 Relay wrote: > > From: Maud Spierings <[email protected]> > > Subject needn't double bindings. > > dt-bindings: backlight: Add max25014 support > > > > > The Maxim MAX25014 is a 4-channel automotive grade backlight driver IC > > with integrated boost controller. > > > > 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. > > Need descript hardware, not driver. Need descript full functions even though > driver have not implement yet. > > > > > Signed-off-by: Maud Spierings <[email protected]> > > --- > > .../bindings/leds/backlight/maxim,max25014.yaml | 109 > > +++++++++++++++++++++ > > MAINTAINERS | 5 + > > 2 files changed, 114 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 0000000000000..496520e1374e5 > > --- /dev/null > > +++ b/Documentation/devicetree/bindings/leds/backlight/maxim,max25014.yaml > > @@ -0,0 +1,109 @@ > > +# 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 <[email protected]> > > + > > +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: > > + $ref: /schemas/types.yaml#/definitions/uint32 > > + maximum: 15 > > + default: 11 > > + description: > > + Value of the ISET register field. This controls the current scale of > > the > > + outputs, a higher number means more current. > > Can't use register value directly, need use standard unit. or percentage > > 100: means max, 0: min.
From that datasheet, it seems like the values here don't neatly map to
currents, because it depends on the value of the iref register. I don't
love percentages here either, too much of a force-fit for me.
If current is used, a property for the reference resistor will be
needed, to compute the register values. That only makes sense to me if
Maxim/Analog provide a formula that can be used to calculate the
appropriate register value, and I did not find one in the datasheet from
my quick skim, only two example current tables.
Sure, those two examples can be reverse-engineered to give a way to
compute it, but can we be sure that the numbers apply across the whole
range of permitted values for the resistor?
I don't like using register values for stuff, but I think it is the most
accurate and least likely to cause problems way of representing this.
Maud, on the language used - its the ISET field in the ISET register, I
think the property should make that clear.
> > +patternProperties:
> > + "^led@[01]$":
Why does this have [01] if reg has to be zero?
> > + 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
>
> there are $ref, should use unevaluatedProperties: false
Not always, looks like they've listed some properties from the file,
which would make addtionalPropeties: false correct if they dont want
the other properties in the file to be used.
>
> Frank
> > +
> > +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>;
> > + enable-gpios = <&gpio1 4 GPIO_ACTIVE_HIGH>;
> > + interrupt-parent = <&gpio1>;
> > + interrupts = <2 IRQ_TYPE_EDGE_FALLING>;
> > + power-supply = <®_backlight>;
> > + pwms = <&pwm1>;
> > + maxim,iset = <7>;
> > +
> > + #address-cells = <1>;
> > + #size-cells = <0>;
> > +
> > + led@0 {
> > + reg = <0>;
> > + led-sources = <0 1 2 3>;
> > + default-brightness = <50>;
> > + };
> > + };
> > + };
> > diff --git a/MAINTAINERS b/MAINTAINERS
> > index 47fbc5e06808f..be5e2515900ce 100644
> > --- a/MAINTAINERS
> > +++ b/MAINTAINERS
> > @@ -15171,6 +15171,11 @@ 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 <[email protected]>
> > +S: Maintained
> > +F: Documentation/devicetree/bindings/leds/backlight/maxim,max25014.yaml
> > +
> > MAX31335 RTC DRIVER
> > M: Antoniu Miclaus <[email protected]>
> > L: [email protected]
> >
> > --
> > 2.51.0
> >
> >
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