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

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Date: Mon, 17 Jun 2024 10:11:53 +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 Krzystof,

> From: Krzysztof Kozlowski <krzk@...nel.org>
> Sent: 2024年6月16日 15:34
> On 13/06/2024 10:48, Aisheng Dong wrote:
> > 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?
> 
> I don't see any problem there. You will have even worse if making it children
> and using populate - unpredictable order.

Sorry I didn't find a good solution without making OCOTP node to be party of SCU
node too which we can't due to extra required properties of nvmem properties. 
E.g. #addr/size-cells.

I think the key problem is OCOTP is already a child node and there's a mismatch issue
If only making secvio, which depends on OCOTP, re-use their parent SCU node.
Maybe you have a good idea. Would you mind share a bit more?

BTW, I don't understand the order problem if making secvio a children as all
child nodes are Individual function devices and supports defer probe well.

Regards
Aisheng

> 
> Best regards,
> Krzysztof
>