linux-kernel - Re: [PATCH 3/5] firmware: arm_scmi: imx: Add LMM and CPU documentation

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Message-ID: <Z72ZxspU3hfGZWez@bogus>
Date: Tue, 25 Feb 2025 10:21:58 +0000
From: Sudeep Holla <sudeep.holla@....com>
To: Peng Fan <peng.fan@....com>
Cc: "Peng Fan (OSS)" <peng.fan@....nxp.com>,
	Chuck Cannon <chuck.cannon@....com>,
	Sudeep Holla <sudeep.holla@....com>,
	Cristian Marussi <cristian.marussi@....com>,
	Shawn Guo <shawnguo@...nel.org>,
	Sascha Hauer <s.hauer@...gutronix.de>,
	"Pengutronix Kernel Team" <kernel@...gutronix.de>,
	Fabio Estevam <festevam@...il.com>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"arm-scmi@...r.kernel.org" <arm-scmi@...r.kernel.org>,
	"linux-arm-kernel@...ts.infradead.org" <linux-arm-kernel@...ts.infradead.org>,
	"imx@...ts.linux.dev" <imx@...ts.linux.dev>
Subject: Re: [PATCH 3/5] firmware: arm_scmi: imx: Add LMM and CPU
 documentation

On Thu, Jan 23, 2025 at 01:30:43AM +0000, Peng Fan wrote:
>
> This is to manage the M7 core by Linux. I just put more documentation here.
> CPU protocol is also used by ATF to manage AP cores.
>

Good

> > Also what other CPUs are we talking here.
>
> M7 core
>

Are they referred by any other name in the system ? I reason I ask is using
plain "CPU" is too generic and confusing. At the same time using "M7" may be
too specific. I am trying to see if there is any middle ground.

> In general I would like to
> > explore the possibility of collapsing this with LM protocol. CPUs within
> > LM is LM's responsibility to bring up. And CPU can be seen as an LM for
> > sake of this vendor protocol. I am not get into details here yet before I
> > can understand what these CPUs are really in the system and why we
> > need this.
>
> Our system supports M7 and A55 in one LM, so A55 use CPU protocol to
> manage M7. When M7 and A55 in different LM, use LM protocol to
> manage M7 LM.
>

The LM(assuming Logical Module/Machine) is an abstract construct, it should
apply to even subset of components within an LM. Just wondering what are
specific reasons do you think applying LM protocol you have on those M7
CPUs alone in A55+M7 LM would not fit well.

--
Regards,
Sudeep