linux-kernel - Re: [PATCH v2 1/5] dt-bindings: remoteproc: sse710: Add the External Systems remote processors

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Message-ID: <20240919145741.GA7940@e130802.arm.com>
Date: Thu, 19 Sep 2024 15:57:41 +0100
From: Abdellatif El Khlifi <abdellatif.elkhlifi@....com>
To: Krzysztof Kozlowski <krzk@...nel.org>
Cc: mathieu.poirier@...aro.org, Adam.Johnston@....com,
	Hugues.KambaMpiana@....com, Drew.Reed@....com, andersson@...nel.org,
	conor+dt@...nel.org, devicetree@...r.kernel.org,
	krzysztof.kozlowski+dt@...aro.org,
	linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
	linux-remoteproc@...r.kernel.org, liviu.dudau@....com,
	lpieralisi@...nel.org, robh@...nel.org, sudeep.holla@....com,
	robin.murphy@....com
Subject: Re: [PATCH v2 1/5] dt-bindings: remoteproc: sse710: Add the External
 Systems remote processors

Hi Krzysztof,

> >>> +  '#extsys-id':
> >>
> >> '#' is not correct for sure, that's not a cell specifier.
> >>
> >> But anyway, we do not accept in general instance IDs.
> > 
> > I'm happy to replace the instance ID with  another solution.
> > In our case the remoteproc instance does not have a base address
> > to use. So, we can't put remoteproc@...ress
> > 
> > What do you recommend in this case please ?
> 
> Waiting one month to respond is a great way to drop all context from my
> memory. The emails are not even available for me - gone from inbox.
> 
> Bus addressing could note it. Or you have different devices, so
> different compatibles. Tricky to say, because you did not describe the
> hardware really and it's one month later...
> 

Sorry for waiting. I was in holidays.

I'll add more documentation about the external system for more clarity [1].

Basically, Linux runs on the Cortex-A35. The External system is a
Cortex-M core. The Cortex-A35 can not access the memory of the Cortex-M.
It can only control Cortex-M core using the reset control and status registers mapped
in the memory space of the Cortex-A35.

I'll make sure this explanation is added to the binding and commit log for
more clarity.

Thanks for the suggestion regarding supporting multiple instances of the
External system. I will send a new version shortly addressing all comments.

[1]: paragraph 2.3, https://developer.arm.com/documentation/dai0550/D/?lang=en

Kind regards
Abdellatif