Re: [PATCH] dt-bindings: display: atmel,lcdc: convert to dtschema

From: Rob Herring <robh@kernel.org>
To: Dharma.B@microchip.com
Cc: devicetree@vger.kernel.org, conor+dt@kernel.org,
	tzimmermann@suse.de, krzysztof.kozlowski+dt@linaro.org,
	linux-kernel@vger.kernel.org, dri-devel@lists.freedesktop.org,
	maarten.lankhorst@linux.intel.com, mripard@kernel.org,
	claudiu.beznea@tuxon.dev, krzysztof.kozlowski@linaro.org,
	alexandre.belloni@bootlin.com, daniel@ffwll.ch,
	airlied@gmail.com, linux-arm-kernel@lists.infradead.org
Subject: Re: [PATCH] dt-bindings: display: atmel,lcdc: convert to dtschema
Date: Fri, 1 Mar 2024 12:10:07 -0600	[thread overview]
Message-ID: <20240301181007.GA2481641-robh@kernel.org> (raw)
In-Reply-To: <dc8181d9-c7c9-4817-96f1-84a1b64575d6@microchip.com>

On Thu, Feb 29, 2024 at 06:25:56AM +0000, Dharma.B@microchip.com wrote:
> On 28/02/24 3:53 pm, Krzysztof Kozlowski wrote:
> > EXTERNAL EMAIL: Do not click links or open attachments unless you know the content is safe
> > 
> > On 28/02/2024 11:18, Dharma.B@microchip.com wrote:
> >> On 28/02/24 12:43 pm, Krzysztof Kozlowski wrote:
> >>> EXTERNAL EMAIL: Do not click links or open attachments unless you know the content is safe
> >>>
> >>> On 28/02/2024 07:59, Dharma.B@microchip.com wrote:
> >>>>
> >>>>>
> >>>>> I don't know what's this exactly, but if embedded display then maybe
> >>>>> could be part of this device node. If some other display, then maybe you
> >>>>> need another schema, with compatible? But first I would check how others
> >>>>> are doing this.
> >>>>
> >>>> Okay, then I think the driver also needs to be modified, currently the
> >>>> driver parses the phandle and looks for these properties. Also the
> >>>> corresponding dts files.
> >>>
> >>> Driver does not have to be modified in my proposal. You would still have
> >>> phandle.
> >>
> >> If I understand correctly, I could define the dt bindings as below
> >>
> >>     display:
> >>       $ref: /schemas/types.yaml#/definitions/phandle
> >>       description: A phandle pointing to the display node.
> >>
> >>     panel:
> >>       $ref: panel/panel-common.yaml#
> >>       properties:
> >>
> > 
> > So these are standard panel bindings? Then the node should live outside
> > of lcdc. If current driver needs to poke inside panel and panel could be
> > anything, then probably you need peripheral-props-like approach. :/
> 
> Thank you so much, so can I use something like this
> 
>    display:
>      $ref: /schemas/types.yaml#/definitions/phandle
>      description: A phandle pointing to the display node.
> 
> patternProperties:
>    "^panel":

Just 'panel' and not a pattern.

However, that's not what the original binding had. It was a separate 
node. If you want to preserve that, then you'll need a separate 
schema file and a special 'select'. Something like:

select:
  anyOf:
    - required: [ atmel,dmacon ]
    - required: [ atmel,lcdcon2 ]
    - required: [ atmel,guard-time ]

Up to you and at91 maintainers if you want to have to update your dts 
files or not.

Rob

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