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

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Message-ID: <CAL_JsqJ4+=L4hOYWKUBRTHpSMfMNaNvEy0xcjX=fZ4r4KP8x3Q@mail.gmail.com>
Date: Wed, 28 Aug 2024 11:11:42 -0500
From: Rob Herring <robh@...nel.org>
To: Lukasz Majewski <lukma@...x.de>
Cc: Pengutronix Kernel Team <kernel@...gutronix.de>, Conor Dooley <conor+dt@...nel.org>, imx@...ts.linux.dev, 
	Shawn Guo <shawnguo@...nel.org>, linux-kernel@...r.kernel.org, 
	linux-arm-kernel@...ts.infradead.org, Fabio Estevam <festevam@...il.com>, 
	Sascha Hauer <s.hauer@...gutronix.de>, devicetree@...r.kernel.org, 
	Krzysztof Kozlowski <krzk+dt@...nel.org>
Subject: Re: [PATCH] dts: nxp: mxs: Add descriptions for imx287 based
 btt3-[012] devices

On Wed, Aug 28, 2024 at 9:12 AM Lukasz Majewski <lukma@...x.de> wrote:
>
> Hi Rob,
>
> > On Wed, 28 Aug 2024 13:21:39 +0200, Lukasz Majewski wrote:
> > > The btt3 device' HW revisions from 0 to 2 use imx287 SoC and are to
> > > some extend similar to already upstreamed XEA devices, hence are
> > > using common imx28-lwe.dtsi file.
> > >
> > > New, btt3.dtsi has been added to embrace common DTS properties for
> > > different HW revisions for this device.
> > >
> > > As a result - changes introduced in btt3-[012].dts are minimal.
> > >
> > > Signed-off-by: Lukasz Majewski <lukma@...x.de>
> > > ---
> > >  arch/arm/boot/dts/nxp/mxs/Makefile   |   3 +
> > >  arch/arm/boot/dts/nxp/mxs/btt3-0.dts |  12 +
> > >  arch/arm/boot/dts/nxp/mxs/btt3-1.dts |   8 +
> > >  arch/arm/boot/dts/nxp/mxs/btt3-2.dts |  12 +
> > >  arch/arm/boot/dts/nxp/mxs/btt3.dtsi  | 320
> > > +++++++++++++++++++++++++++ 5 files changed, 355 insertions(+)
> > >  create mode 100644 arch/arm/boot/dts/nxp/mxs/btt3-0.dts
> > >  create mode 100644 arch/arm/boot/dts/nxp/mxs/btt3-1.dts
> > >  create mode 100644 arch/arm/boot/dts/nxp/mxs/btt3-2.dts
> > >  create mode 100644 arch/arm/boot/dts/nxp/mxs/btt3.dtsi
> > >
> >
> >
> > My bot found new DTB warnings on the .dts files added or changed in
> > this series.
> >
> > Some warnings may be from an existing SoC .dtsi. Or perhaps the
> > warnings are fixed by another series. Ultimately, it is up to the
> > platform maintainer whether these warnings are acceptable or not. No
> > need to reply unless the platform maintainer has comments.
> >
>
> There a few things to clarify after:
> CROSS_COMPILE="arm-none-linux-gnueabihf-"
> ARCH=arm make -j4 CHECK_DTBS=y nxp/mxs/btt3-0.dtb
>
> 1. mxs-spi.yaml vs mxs-mmc.yaml -> both refer to the same set of HW - as
> those IP blocks can work as both mmc and SPI.

Sounds like there should be 1 binding then.

>
> 2. For the sound codec:
>  codec@1a: compatible: ['wlf,wm8940', 'wlf,wm8974'] is too long
>
> This is a bit problematic as well - as WM8974 doesn't have ANY ID
> register, so it needs to be probed manually and decided which module
> with sound codec needs to be inserted. The WM8940 is the pin compatible
> replacement.

So if the OS has 2 drivers for these 2 devices, which one does it
pick? The answer for Linux is it is undefined. The expectation is if
there are multiple options, the firmware figures out which one is
present and adjusts the DT.

> 3. The simple-bus.yaml seems to be missing in the Linux kernel tree -
> problem is that imx28 has 'apbx' bus.

simple-bus.yaml lives in dtschema repo.

Node names should be generic, not named for the implementation/type.
The binding is fairly flexible in allowing ".*-bus".

> 4. The fsl,lcdif.yaml doesn't allow the situation when one specify by
> hand (in DTS) display parameters (as different ones can be used by the
> manufacturing site).

Shrug. At the end of the day, the binding and dts have to match. One
(or both) has to be adjusted.

Rob