linux-kernel - Re: [PATCH v3 1/4] dt-bindings: backlight: Add max25014 bindingsy

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Message-ID: <aMQ6rZJzbMeBrrFv@lizhi-Precision-Tower-5810>
Date: Fri, 12 Sep 2025 11:22:21 -0400
From: Frank Li <Frank.li@....com>
To: Maud Spierings <maudspierings@...ontroll.com>
Cc: Lee Jones <lee@...nel.org>, Daniel Thompson <danielt@...nel.org>,
	Jingoo Han <jingoohan1@...il.com>, Pavel Machek <pavel@...nel.org>,
	Rob Herring <robh@...nel.org>,
	Krzysztof Kozlowski <krzk+dt@...nel.org>,
	Conor Dooley <conor+dt@...nel.org>, Helge Deller <deller@....de>,
	Shawn Guo <shawnguo@...nel.org>,
	Sascha Hauer <s.hauer@...gutronix.de>,
	Pengutronix Kernel Team <kernel@...gutronix.de>,
	Fabio Estevam <festevam@...il.com>, dri-devel@...ts.freedesktop.org,
	linux-leds@...r.kernel.org, devicetree@...r.kernel.org,
	linux-kernel@...r.kernel.org, linux-fbdev@...r.kernel.org,
	imx@...ts.linux.dev, linux-arm-kernel@...ts.infradead.org
Subject: Re: [PATCH v3 1/4] dt-bindings: backlight: Add max25014 bindingsy

On Fri, Sep 12, 2025 at 08:17:09AM +0200, Maud Spierings wrote:
> Hi Frank,
> Thanks for the review.
>
> On 9/11/25 17:33, Frank Li wrote:
> > On Thu, Sep 11, 2025 at 09:53:18AM +0200, Maud Spierings via B4 Relay wrote:
> > > From: Maud Spierings <maudspierings@...ontroll.com>
> > >
> > > The Maxim MAX25014 is a 4-channel automotive grade backlight driver IC
> > > with integrated boost controller.
> > >
> > > Signed-off-by: Maud Spierings <maudspierings@...ontroll.com>
> > > ---
> > >   .../bindings/leds/backlight/maxim,max25014.yaml    | 81 ++++++++++++++++++++++
> > >   MAINTAINERS                                        |  5 ++
> > >   2 files changed, 86 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 0000000000000000000000000000000000000000..e113a2ad16aa74f982b9c2ea80578aed2d9424fe
> > > --- /dev/null
> > > +++ b/Documentation/devicetree/bindings/leds/backlight/maxim,max25014.yaml
> > > @@ -0,0 +1,81 @@
> > > +# 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@...ontroll.com>
> > > +
> > > +allOf:
> > > +  - $ref: common.yaml#
> > > +
> > > +properties:
> > > +  compatible:
> > > +    enum:
> > > +      - maxim,max25014
> > > +
> > > +  reg:
> > > +    maxItems: 1
> > > +
> > > +  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.
> >
> > Use standard unit. Do not use register value directly.
>
> It is unfortunately not just a value in Amps, it depends on the hardware
> design. There is a kind of "default" table with a 49.9K resistor, but
> depending on that resistor the current is different.

You should calculate in your driver. if 49.9K is dependence, you should
add xxx_ohm at dts.

Frank

>
> > > +
> > > +  maxim,strings:
> > > +    $ref: /schemas/types.yaml#/definitions/uint32-array
> > > +    description:
> > > +      A 4-bit bitfield that describes which led strings to turn on.
> > > +    minItems: 4
> > > +    maxItems: 4
> > > +    items:
> > > +      maximum: 1
> >
> > led should have standard interface.
> >
> > check  Documentation/devicetree/bindings/leds/common.yaml
>
> Thanks I will investigate, that may indeed be a better abstraction.
>
> Kind regards,
> Maud
>