linux-kernel - Re: [PATCH v6 2/2] dts: nxp: mxs: Add descriptions for imx287 based btt3-[012] devices

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Message-ID: <20240923114711.1c294b6b@wsk>
Date: Mon, 23 Sep 2024 11:47:11 +0200
From: Lukasz Majewski <lukma@...x.de>
To: Fabio Estevam <festevam@...il.com>, Rob Herring <robh@...nel.org>
Cc: Krzysztof Kozlowski <krzk+dt@...nel.org>, Conor Dooley
 <conor+dt@...nel.org>, Shawn Guo <shawnguo@...nel.org>, Sascha Hauer
 <s.hauer@...gutronix.de>, Pengutronix Kernel Team <kernel@...gutronix.de>,
 devicetree@...r.kernel.org, imx@...ts.linux.dev,
 linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v6 2/2] dts: nxp: mxs: Add descriptions for imx287 based
 btt3-[012] devices

Hi Fabio,

> Hi Lukasz,
> 
> On Thu, Sep 12, 2024 at 9:48 AM Lukasz Majewski <lukma@...x.de> wrote:
> 
> > +&lcdif {
> > +       pinctrl-names = "default";
> > +       pinctrl-0 = <&lcdif_24bit_pins_a>, <&lcdif_sync_pins_bttc>,
> > +                   <&lcdif_reset_pins_bttc>;
> > +       lcd-supply = <&reg_3v3>;
> > +       display = <&display0>;
> > +       status = "okay";
> > +       display0: display0 {
> > +               bits-per-pixel = <32>;
> > +               bus-width = <24>;
> > +               display-timings {
> > +                       native-mode = <&timing0>;
> > +                       timing0: timing0 {
> > +                               clock-frequency = <6500000>;
> > +                               hactive = <320>;
> > +                               vactive = <240>;
> > +                               hfront-porch = <20>;
> > +                               hback-porch = <38>;
> > +                               hsync-len = <30>;
> > +                               vfront-porch = <4>;
> > +                               vback-porch = <14>;
> > +                               vsync-len = <4>;
> > +                               hsync-active = <0>;
> > +                               vsync-active = <0>;
> > +                               de-active = <0>;
> > +                               pixelclk-active = <1>;  
> 
> According to fsl,lcdif.yaml, a remote-endpoint to the display is
> needed.
> 
> See imx28-evk.dts for an example.

This file has the:
	panel {
		compatible = "sii,43wvf1g";

Whereas in those devices (i.e. btt3) - I don't know the names of the
displays - manufacturer buys them according to the timing properties.

Hence the question - how shall I proceed?

IMHO the most straightforward way is to modify fsl,lcdif.yaml to
not require "port" and "remote-endpoint" and instead add support for
"display-timings" and "timingX"

Especially that
Documentation/devicetree/bindings/display/panel/display-timings.yaml

are already defined and used by many imx boards (from imx25 to imx6q)
- git grep -n "display-timings"

Even the imx28-m28evk.dts is using the "display-timings" and not
"remote-endpoint" approach.


Best regards,

Lukasz Majewski

--

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