Re: [RFC PATCH 02/16] dt-bindings: display: rockchip: Add EBC binding

From: Andreas Kemnade <andreas@kemnade.info>
To: Samuel Holland <samuel@sholland.org>
Cc: "Heiko Stübner" <heiko@sntech.de>,
	"Sandy Huang" <hjc@rock-chips.com>,
	dri-devel@lists.freedesktop.org,
	linux-rockchip@lists.infradead.org,
	"Alistair Francis" <alistair@alistair23.me>,
	"Ondřej Jirman" <x@xff.cz>, "Daniel Vetter" <daniel@ffwll.ch>,
	"David Airlie" <airlied@linux.ie>,
	"Geert Uytterhoeven" <geert@linux-m68k.org>,
	"Krzysztof Kozlowski" <krzk+dt@kernel.org>,
	"Liang Chen" <cl@rock-chips.com>,
	"Maarten Lankhorst" <maarten.lankhorst@linux.intel.com>,
	"Maxime Ripard" <mripard@kernel.org>,
	"Michael Riesch" <michael.riesch@wolfvision.net>,
	"Nicolas Frattaroli" <frattaroli.nicolas@gmail.com>,
	"Peter Geis" <pgwipeout@gmail.com>,
	"Rob Herring" <robh+dt@kernel.org>,
	"Sam Ravnborg" <sam@ravnborg.org>,
	"Thierry Reding" <thierry.reding@gmail.com>,
	"Thomas Zimmermann" <tzimmermann@suse.de>,
	devicetree@vger.kernel.org, linux-arm-kernel@lists.infradead.org,
	linux-kernel@vger.kernel.org
Subject: Re: [RFC PATCH 02/16] dt-bindings: display: rockchip: Add EBC binding
Date: Thu, 14 Apr 2022 10:15:48 +0200	[thread overview]
Message-ID: <20220414101548.2b9c3dad@aktux> (raw)
In-Reply-To: <20220413221916.50995-3-samuel@sholland.org>

Hi Samuel,

for comparison, here is my submission for the IMX EPDC bindings:

https://lore.kernel.org/linux-devicetree/20220206080016.796556-2-andreas@kemnade.info/

On Wed, 13 Apr 2022 17:19:02 -0500
Samuel Holland <samuel@sholland.org> wrote:

[...]
we have sy7636a driver in kernel which should be suitable for powering a EPD
and temperature measurement. So I would expect that to be 
> +  io-channels:
> +    maxItems: 1
> +    description: I/O channel for panel temperature measurement
> +
so how would I reference the hwmon/thermal(-zone) of the sy7636a here?

> +  panel-supply:
> +    description: Regulator supplying the panel's logic voltage
> +
> +  power-domains:
> +    maxItems: 1
> +
> +  vcom-supply:
> +    description: Regulator supplying the panel's compensation voltage
> +
> +  vdrive-supply:
> +    description: Regulator supplying the panel's gate and source drivers
> +
SY7636a has only one logical regulator in kernel for for the latter two.

If we have a separate panel node, than maybe these regulators should go
there as they belong to the panel as they are powering the panel and
not the EBC.

> +  port:
> +    $ref: /schemas/graph.yaml#/properties/port
> +    description: OF graph port for the attached display panel
> +
In my approach for the IMX EPDC, (I will send a better commented one
soon) I have no separate subnode to avoid messing with additional
display parameters. Not sure what is really better here.

> +required:
> +  - compatible
> +  - reg
> +  - interrupts
> +  - clocks
> +  - clock-names
> +  - resets
> +  - reset-names
> +  - power-domains
> +  - panel-supply
> +  - vcom-supply
> +  - vdrive-supply

If things differ how the different phyiscally existing regulators are
mapped into logical ones (even the vdrive supply is still a bunch of
physical regulators mapped into one logical one), then not everything
can be required.

Regards,
Andreas

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