linux-kernel - Re: [PATCH 3/3] ARM: dts: mxs: support i.MX28 Amarula rmm board

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Message-ID: <CABGWkvpPMry26DP4Wo8WEGhokdkf5GdLd=+O5SqRdh-8JBqt_w@mail.gmail.com>
Date: Wed, 21 May 2025 15:19:48 +0200
From: Dario Binacchi <dario.binacchi@...rulasolutions.com>
To: Fabio Estevam <festevam@...il.com>
Cc: linux-kernel@...r.kernel.org, linux-amarula@...rulasolutions.com, 
	michael@...rulasolutions.com, Conor Dooley <conor+dt@...nel.org>, 
	Krzysztof Kozlowski <krzk+dt@...nel.org>, Pengutronix Kernel Team <kernel@...gutronix.de>, 
	Rob Herring <robh@...nel.org>, Sascha Hauer <s.hauer@...gutronix.de>, 
	Shawn Guo <shawnguo@...nel.org>, devicetree@...r.kernel.org, imx@...ts.linux.dev, 
	linux-arm-kernel@...ts.infradead.org
Subject: Re: [PATCH 3/3] ARM: dts: mxs: support i.MX28 Amarula rmm board

Hi Fabio,

On Wed, May 21, 2025 at 1:40 PM Fabio Estevam <festevam@...il.com> wrote:
>
> Hi Dario,
>
> On Wed, May 21, 2025 at 6:28 AM Dario Binacchi
> <dario.binacchi@...rulasolutions.com> wrote:
> >
> > The board includes the following resources:
> >  - 256 Mbytes NAND Flash
> >  - 256 Mbytes SRAM
>
> SRAM or DDR?

Sorry, DRAM DDR2

>
> >  - LCD-TFT controller
>
> The LCD support is not described in the dts.

Yes, you're right.
The board has been in use for a long time with a 4.19 kernel. We recently bumped
it to the LTS version 6.6.69. However, for now we've had to revert commit
f225f1393f034 ("video: fbdev: mxsfb: Remove driver") along with other
custom changes
to reproduce the correct display behavior in the field. That's why we
haven't described
the LCD panel yet.
We'd like to add it only after we get it working without needing to
apply non-mainline patches.

The same goes for the sound, which is neither mentioned in the commit
description nor in the DTS.

So if you're okay with it, I will remove all references to the LCD
display — both from the commit
message and from the DTS, such as the reset pin, for example.

>
> > +/ {
> > +       model = "Amarula i.MX28 rmm";
> > +       compatible = "amarula,imx28-rmm", "fsl,imx28";
> > +
> > +       memory@...00000 {
> > +               device_type = "memory";
> > +               reg = <0x40000000 0x08000000>;
>
> In the commit log, you say 256 MB, but here we have 128 MB.

We have two models, one with 128MB and one with 256MB of RAM.
What's the recommended way to handle both cases?
Should I define a new DTS file named imx28-amarula-rmm-256mb.dts
that includes imx28-amarula-rmm.dts and override the reg property of
the memory node?

>
> > +&i2c0 {
> > +       pinctrl-names = "default";
> > +       pinctrl-0 = <&i2c0_pins_a>;
> > +       status = "okay";
> > +
> > +       polytouch: edt-ft5x06@38 {
>
> Node names should be generic: touchscreen@38

Ok

>
> > +
> > +&pinctrl {
> > +       pinctrl-names = "default";
> > +       pinctrl-0 = <&hog_pins_a>;
> > +
> > +       hog_pins_a: hog-0 {
> > +               reg = <0>;
> > +               fsl,pinmux-ids = <
> > +                       MX28_PAD_LCD_RESET__GPIO_3_30 /* LCD reset */
> > +                       MX28_PAD_SSP2_SS1__GPIO_2_20  /* External power */
>
> Proper panel bindings should better describe these pins than hog pins.

I will drop the LCD reset pin.

Thanks and regards,
Dario

>
> Do you plan to add display support?



-- 

Dario Binacchi

Senior Embedded Linux Developer

dario.binacchi@...rulasolutions.com

__________________________________


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Via Le Canevare 30, 31100 Treviso, Veneto, IT

T. +39 042 243 5310
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