linux-kernel - Re: [PATCH v3 0/3] Convert Microchip's HLCDC Text based DT bindings to JSON schema

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Date: Fri, 19 Jan 2024 08:41:04 +0000
From: <Dharma.B@...rochip.com>
To: <sam@...nborg.org>
CC: <Conor.Dooley@...rochip.com>, <bbrezillon@...nel.org>,
	<maarten.lankhorst@...ux.intel.com>, <mripard@...nel.org>,
	<tzimmermann@...e.de>, <airlied@...il.com>, <daniel@...ll.ch>,
	<robh+dt@...nel.org>, <krzysztof.kozlowski+dt@...aro.org>,
	<conor+dt@...nel.org>, <Nicolas.Ferre@...rochip.com>,
	<alexandre.belloni@...tlin.com>, <claudiu.beznea@...on.dev>,
	<dri-devel@...ts.freedesktop.org>, <devicetree@...r.kernel.org>,
	<linux-arm-kernel@...ts.infradead.org>, <linux-kernel@...r.kernel.org>,
	<lee@...nel.org>, <thierry.reding@...il.com>,
	<u.kleine-koenig@...gutronix.de>, <linux-pwm@...r.kernel.org>,
	<Linux4Microchip@...rochip.com>
Subject: Re: [PATCH v3 0/3] Convert Microchip's HLCDC Text based DT bindings
 to JSON schema

Hi Sam,
On 19/01/24 1:00 am, Sam Ravnborg wrote:
> [You don't often get email from sam@...nborg.org. Learn why this is important at https://aka.ms/LearnAboutSenderIdentification ]
> 
> EXTERNAL EMAIL: Do not click links or open attachments unless you know the content is safe
> 
> Hi Dharma et al.
> 
> On Thu, Jan 18, 2024 at 02:56:09PM +0530, Dharma Balasubiramani wrote:
>> Converted the text bindings to YAML and validated them individually using following commands
>>
>> $ make dt_binding_check DT_SCHEMA_FILES=Documentation/devicetree/bindings/
>> $ make dtbs_check DT_SCHEMA_FILES=Documentation/devicetree/bindings/
>>
>> changelogs are available in respective patches.
>>
>> Dharma Balasubiramani (3):
>>    dt-bindings: display: convert Atmel's HLCDC to DT schema
>>    dt-bindings: atmel,hlcdc: convert pwm bindings to json-schema
>>    dt-bindings: mfd: atmel,hlcdc: Convert to DT schema format
> 
> I know this is a bit late to ask - sorry in advance.
> 
> The binding describes the single IP block as a multi functional device,
> but it is a single IP block that includes the display controller and a
> simple pwm that can be used for contrast or backlight.
yes.
> 
> If we ignore the fact that the current drivers for hlcdc uses an mfd
> abstraction, is this then the optimal way to describe the HW?
> 
> 
> In one of my stale git tree I converted atmel lcdc to DT, and here
Are you referring the "bindings/display/atmel,lcdc.txt"?
> I used:
> 
> +  "#pwm-cells":
> +    description:
> +      This PWM chip use the default 3 cells bindings
> +      defined in ../../pwm/pwm.yaml.
> +    const: 3
> +
> +  clocks:
> +    maxItems: 2
> +
> +  clock-names:
> +    maxItems: 2
> +    items:
> +      - const: lcdc_clk
> +      - const: hclk
> 
> This proved to be a simple way to describe the HW.
> 
> To make the DT binding backward compatible you likely need to add a few
> compatible that otherwise would have been left out - but that should do
> the trick.
again you mean the compatibles from atmel,lcdc binding?
> 
> The current atmel hlcdc driver that is split in three is IMO an
> over-engineering, and the driver could benefit merging it all in one.
> And the binding should not prevent this.
could you please confirm if my understanding is correct: you want a 
unified display binding that encompasses the properties of the two 
subdevices (display controller and pwm), eliminating the need to 
reference them in additional bindings?
> 
>          Sam

-- 
With Best Regards,
Dharma B.