linux-kernel - Re: [PATCH V2 1/2] clk: imx: add mcore

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Message-Id: <20220317193717.33264C340E9@smtp.kernel.org>
Date:   Thu, 17 Mar 2022 12:37:15 -0700
From:   Stephen Boyd <sboyd@...nel.org>
To:     Peng Fan (OSS) <peng.fan@....nxp.com>, abel.vesa@....com,
        s.hauer@...gutronix.de, shawnguo@...nel.org
Cc:     kernel@...gutronix.de, festevam@...il.com, linux-imx@....com,
        linux-clk@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        linux-kernel@...r.kernel.org, Peng Fan <peng.fan@....com>
Subject: Re: [PATCH V2 1/2] clk: imx: add mcore_booted module paratemter

Quoting Peng Fan (OSS) (2022-02-28 04:41:11)
> From: Peng Fan <peng.fan@....com>
> 
> Add mcore_booted boot parameter which could simplify AMP clock
> management. To i.MX8M, there is CCM(clock control Module) to generate
> clock root clock, anatop(analog PLL module) to generate PLL, and CCGR
> (clock gating) to gate clocks to peripherals. As below:
>   anatop->ccm->ccgr->peripheral
> 
> Linux handles the clock management and the auxiliary core is under
> control of Linux. Although there is per hardware domain control for CCGR
> and CCM, auxiliary core normally only use CCGR hardware domain control
> to avoid linux gate off the clk to peripherals and leave CCM ana anatop
> to Linux.
> 
> Per NXP hardware design, because CCGR already support gate to
> peripherals, and clk root gate power leakage is negligible. So
> when in AMP case, we could not register the clk root gate.
> 
> Signed-off-by: Peng Fan <peng.fan@....com>
> ---
> 
> V2:
>  Switch to use module parameter, tested on i.MX8MP-EVK

Why is a module parameter being used? I'd expect this informatioon that
mcore is booted to come from devicetree/firmware somehow.