linux-kernel - Re: [PATCH v2 01/20] dt-bindings: display: tilcdc: Convert to DT schema

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Message-ID: <20251217122054.4682c6dd@kmaincent-XPS-13-7390>
Date: Wed, 17 Dec 2025 12:20:54 +0100
From: Kory Maincent <kory.maincent@...tlin.com>
To: Krzysztof Kozlowski <krzk@...nel.org>
Cc: Jyri Sarha <jyri.sarha@....fi>, Tomi Valkeinen
 <tomi.valkeinen@...asonboard.com>, Maarten Lankhorst
 <maarten.lankhorst@...ux.intel.com>, Maxime Ripard <mripard@...nel.org>,
 Thomas Zimmermann <tzimmermann@...e.de>, David Airlie <airlied@...il.com>,
 Simona Vetter <simona@...ll.ch>, Rob Herring <robh@...nel.org>, Krzysztof
 Kozlowski <krzk+dt@...nel.org>, Conor Dooley <conor+dt@...nel.org>, Russell
 King <linux@...linux.org.uk>, Bartosz Golaszewski <brgl@...ev.pl>, Tony
 Lindgren <tony@...mide.com>, Andrzej Hajda <andrzej.hajda@...el.com>, Neil
 Armstrong <neil.armstrong@...aro.org>, Robert Foss <rfoss@...nel.org>,
 Laurent Pinchart <Laurent.pinchart@...asonboard.com>, Jonas Karlman
 <jonas@...boo.se>, Jernej Skrabec <jernej.skrabec@...il.com>, Markus
 Schneider-Pargmann <msp@...libre.com>, Bajjuri Praneeth <praneeth@...com>,
 Luca Ceresoli <luca.ceresoli@...tlin.com>, Louis Chauvet
 <louis.chauvet@...tlin.com>, Thomas Petazzoni
 <thomas.petazzoni@...tlin.com>, Miguel Gazquez
 <miguel.gazquez@...tlin.com>, dri-devel@...ts.freedesktop.org,
 devicetree@...r.kernel.org, linux-kernel@...r.kernel.org,
 linux-arm-kernel@...ts.infradead.org, linux-omap@...r.kernel.org
Subject: Re: [PATCH v2 01/20] dt-bindings: display: tilcdc: Convert to DT
 schema

On Tue, 16 Dec 2025 07:01:49 +0100
Krzysztof Kozlowski <krzk@...nel.org> wrote:

> On Thu, Dec 11, 2025 at 05:38:45PM +0100, Kory Maincent (TI.com) wrote:
> > diff --git a/Documentation/devicetree/bindings/display/tilcdc/tilcdc.yaml
> > b/Documentation/devicetree/bindings/display/tilcdc/tilcdc.yaml new file
> > mode 100644 index 0000000000000..34ac1fd04d5c6
> > --- /dev/null
> > +++ b/Documentation/devicetree/bindings/display/tilcdc/tilcdc.yaml  
> 
> Filename based on compatible, so for example ti,am33xx-tilcdc.yaml or
> worse case ti,tilcdc.yaml (see writing bindings and writing schema docs)

Oh indeed forgot that rule. Sorry.
 
> > @@ -0,0 +1,96 @@
> > +# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
> > +%YAML 1.2
> > +---
> > +$id: http://devicetree.org/schemas/display/tilcdc/tilcdc.yaml#
> > +$schema: http://devicetree.org/meta-schemas/core.yaml#
> > +
> > +title: TI LCD Controller, found on AM335x, DA850, AM18x and OMAP-L138
> > +
> > +maintainers:
> > +  - Kory Maincent <kory.maincent@...tlin.com>
> > +
> > +properties:
> > +  compatible:
> > +    enum:
> > +      - ti,am33xx-tilcdc
> > +      - ti,da850-tilcdc
> > +
> > +  reg:
> > +    maxItems: 1
> > +
> > +  interrupts:
> > +    maxItems: 1
> > +
> > +  port:
> > +    $ref: /schemas/graph.yaml#/properties/port
> > +
> > +  ti,hwmods:
> > +    $ref: /schemas/types.yaml#/definitions/string
> > +    description:
> > +      Name of the hwmod associated to the LCDC
> > +
> > +  max-bandwidth:  
> 
> constraints? Is '1' valid? Is INT_MAX valid as well?

These maximums values are kind of software only check. See:
https://elixir.bootlin.com/linux/v6.18.1/source/drivers/gpu/drm/tilcdc/tilcdc_crtc.c#L846
but there are no mainline devicetree using it. We have to keep them because
they were present in the text binding.

I think we can still add a maximum constraint matching the tilcdc maximum
resolution value.

...

> Drop unused label. Generic node name, e.g. "display-controller" or
> "lcd-controller".

Ok, thank you for the review!

Regards,
-- 
Köry Maincent, Bootlin
Embedded Linux and kernel engineering
https://bootlin.com