linux-kernel - RE: [PATCH 1/2] dt-bindings: leds: Document LTC3220 18 channel LED Driver

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Message-ID:
 <PH0PR03MB6525F2AB63E24564356ADE51ED84A@PH0PR03MB6525.namprd03.prod.outlook.com>
Date: Wed, 7 Jan 2026 09:52:19 +0000
From: "Escala, Edelweise" <Edelweise.Escala@...log.com>
To: Krzysztof Kozlowski <krzk@...nel.org>
CC: Lee Jones <lee@...nel.org>, Pavel Machek <pavel@...nel.org>,
        Rob Herring
	<robh@...nel.org>,
        Krzysztof Kozlowski <krzk+dt@...nel.org>,
        Conor Dooley
	<conor+dt@...nel.org>,
        "linux-leds@...r.kernel.org"
	<linux-leds@...r.kernel.org>,
        "devicetree@...r.kernel.org"
	<devicetree@...r.kernel.org>,
        "linux-kernel@...r.kernel.org"
	<linux-kernel@...r.kernel.org>
Subject: RE: [PATCH 1/2] dt-bindings: leds: Document LTC3220 18 channel LED
 Driver

> On Tue, Jan 06, 2026 at 01:27:07PM +0800, Edelweise Escala wrote:
> > Add dt-binding for ltc3220. LTC3220 18 Channel LED driver
> 
> Subject, commit msg, binding: driver as Linux driver? If yes, then rewrite
> everything to match hardware.
> 
> Otherwise what is exactly a LED driver? I know motor drivers.
> 

I will rewrite to match hardware.

> >
> > Signed-off-by: Edelweise Escala <edelweise.escala@...log.com>
> > ---
> >  .../devicetree/bindings/leds/leds-ltc3220.yaml     | 131
> +++++++++++++++++++++
> >  MAINTAINERS                                        |   7 ++
> >  2 files changed, 138 insertions(+)
> >
> > diff --git a/Documentation/devicetree/bindings/leds/leds-ltc3220.yaml
> > b/Documentation/devicetree/bindings/leds/leds-ltc3220.yaml
> > new file mode 100644
> > index 000000000000..33285a7ac7a3
> > --- /dev/null
> > +++ b/Documentation/devicetree/bindings/leds/leds-ltc3220.yaml
> 
> Filename matching compatible.
> 
> 
> > @@ -0,0 +1,131 @@
> > +# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause) %YAML 1.2
> > +---
> > +$id:
> > +https://urldefense.com/v3/__http://devicetree.org/schemas/leds/leds-l
> > +tc3220.yaml*__;Iw!!A3Ni8CS0y2Y!-
> bTmoOEA7bjPt5CM_hEEqaRU4x0nvJNS2Y926U
> > +ULgO8UsbmEQwBUHq-AZjzofrOg5HnnWnBflY9LKFGVrA$
> > +$schema:
> > +https://urldefense.com/v3/__http://devicetree.org/meta-schemas/core.y
> > +aml*__;Iw!!A3Ni8CS0y2Y!-
> bTmoOEA7bjPt5CM_hEEqaRU4x0nvJNS2Y926UULgO8Usb
> > +mEQwBUHq-AZjzofrOg5HnnWnBflY9BRg_sig$
> > +
> > +title: Analog Devices LTC3220 LED Drivers
> > +
> > +maintainers:
> > +  - Edelweise Escala <edelweise.escala@...log.com>
> > +
> > +description: Bindings for the Analog Devices LTC3220 18 channel LED
> Drivers.
> 
> Missing wrapping after description. Look at other bindings.
> 
> Also, drop "Bindings for". You should describe  here hardware, not that
> binding is a binding for.
> 

I will fix the missing wrapping and improve the description.

> > +
> > +  For more product information please see the link below
> > +    https://www.analog.com/en/products/ltc3220.html
> > +
> > +properties:
> > +  compatible:
> > +    enum:
> > +      - adi,ltc3220
> > +      - adi,ltc3220-1
> 
> What is -1 device? Why description does not help here at all?
> 

It is just a version of ltc3220 with different slave address, I will drop it.

> > +
> > +  reg:
> > +    maxItems: 1
> > +
> > +  '#address-cells':
> > +    const: 1
> > +
> > +  '#size-cells':
> > +    const: 0
> > +
> > +  reset-gpios:
> > +    maxItems: 1
> > +    description: GPIO attached to the chip's reset pin
> 
> Drop description, obvious, redundant.
> 
> > +
> > +  adi,force-cpo-level:
> > +    $ref: /schemas/types.yaml#/definitions/string
> > +    description: Forces the Charge Pump Output to a specified multiplier.
> > +    enum:
> > +      - "0" # Auto(default) - Automatically selects optimal charge pump mode
> > +      - "1.5"
> > +      - "2"
> > +      - "1"
> 
> Numbers are not a string, so choose appropriate number format. Also, oddly
> sorted. I don't understand what this property is for so not sure what to
> recommend.

It is arranged this way to match the value for the register.
I plan to keep it as string and just do 
enum:
- auto
- 1.5x
- 2x
- 1x

> 
> > +    default: "0"
> > +
> > +  adi,quick-write:
> > +    type: boolean
> > +    description: If present, LED 1 output becomes a master control that
> > +      simultaneously updates all 18 LED outputs using the hardware's quick-
> write
> > +      mode. When enabled, led@1 must be defined in the device tree to
> provide
> > +      the control interface, even if no physical LED is connected to the D1
> > +      output pin. When disabled or not present, LED 1 operates as a normal
> > +      independent LED output.
> 
> If there is no led@1 physically, you cannot add it to the DT. It seems you
> described some sort of driver behavior, instead of hardware.
> 

This is also a hardware feature, when enabled a write to the LED 1
output register simultaneously updates all 18 LED output registers
to the same value.

> > +
> > +patternProperties:
> > +  "^led@([1-9]|1[0-8])$":
> 
> Use consistent quotes, so '.
> 
> > +    type: object
> > +    $ref: /schemas/leds/common.yaml#
> > +    unevaluatedProperties: false
> > +    properties:
> > +      reg:
> > +        description: Output channel for the LED (1-18 maps to LED outputs
> D1-D18).
> > +        minimum: 1
> > +        maximum: 18
> 

Best Regards,
Edelweise