linux-kernel - RE: [PATCH 1/4] dt-bindings: firmware: secvio: Add device tree bindings

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Date: Thu, 13 Jun 2024 08:48:00 +0000
From: Aisheng Dong <aisheng.dong@....com>
To: Krzysztof Kozlowski <krzk@...nel.org>, Vabhav Sharma
	<vabhav.sharma@....com>, Rob Herring <robh@...nel.org>, Krzysztof Kozlowski
	<krzk+dt@...nel.org>, Conor Dooley <conor+dt@...nel.org>, Franck Lenormand
	<franck.lenormand@....com>, Shawn Guo <shawnguo@...nel.org>, Sascha Hauer
	<s.hauer@...gutronix.de>, Pengutronix Kernel Team <kernel@...gutronix.de>,
	Fabio Estevam <festevam@...il.com>, Peng Fan <peng.fan@....com>
CC: "devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"imx@...ts.linux.dev" <imx@...ts.linux.dev>,
	"linux-arm-kernel@...ts.infradead.org"
	<linux-arm-kernel@...ts.infradead.org>, Varun Sethi <V.Sethi@....com>,
	Silvano Di Ninno <silvano.dininno@....com>, Pankaj Gupta
	<pankaj.gupta@....com>, Frank Li <frank.li@....com>, Daniel Baluta
	<daniel.baluta@....com>
Subject: RE: [PATCH 1/4] dt-bindings: firmware: secvio: Add device tree
 bindings

Hi Krzysztof, 

> From: Krzysztof Kozlowski <krzk@...nel.org>
> Sent: 2024年6月13日 14:14
> 
> On 12/06/2024 09:20, Aisheng Dong wrote:
> > Hi Krzysztof
> >
> >> From: Krzysztof Kozlowski <krzk@...nel.org>
> >> Sent: 2024年6月7日 15:08
> >>
> >> On 07/06/2024 06:58, Vabhav Sharma wrote:
> >>>>
> >>>> Missing SoC compatibles.
> >>> Ok, I will use fsl,imx8dxl-sc-secvio
> >>>>
> >>>> So no, that's just abuse of DT to instantiate driver.
> >>>>
> >>>> NAK. Drop the binding.
> >>> I will detail the dt binding to describe the real hardware
> >>
> >> Still looks like way just to instantiate driver. Why it cannot be
> >> part of existing firmware SCU node?
> >>
> >
> > Technically yes. But SCU case is a little bit complicated as there're
> > many functions and all of them are already added as sub nodes in SCU
> > node for consistency and handling platform difference.
> >
> > I guess some of them, e.g. rtc, could be part of SCU node (reuse)
> > while some couldn't. e.g. pinctrl Do you want us to only make secvio
> > reuse existing SCU node?
> 
> Yes
> 

Digging a bit more on the implementation. It seems there will be a
'parent depends on child' issue when reusing the parent SCU node for secvio.
Considering the defer probe support and ocotop could be modules, I'm still thinking
If any solution. Do you have a good suggestion?

e.g.
system-controller {
        compatible = "fsl,imx-scu";
		nvmem = <&ocotp>;
        ...

        ocotp: ocotp {
                compatible = "fsl,imx8qxp-scu-ocotp";
                #address-cells = <1>;
                #size-cells = <1>;
                read-only;
        };
		...
}

static int imx_scu_probe(struct platform_device *pdev)
{
		...
        ret = imx_secvio_sc_setup(dev);
        if (ret)
                dev_warn(dev, "failed to initialize secvio: %d\n", ret);
		...
        return devm_of_platform_populate(dev);
}

Regards
Aisheng

> > This might look a bit strange to the existing sub nodes.
> 
> Nothing strange/unusual to me.
> 
> >
> > BTW, even we can reuse SCU node for secvio function, we still need
> > update binding doc to add extra property 'nvmem' for secvio.
> 
> Sure.
> 
> 
> 
> Best regards,
> Krzysztof