linux-kernel - Re: [PATCH 3/3] cpufreq: imx-sc: add i.mx system controller cpufreq support

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Message-ID: <20190213101502.v75d3nfwctcks2gx@vireshk-i7>
Date:   Wed, 13 Feb 2019 15:45:02 +0530
From:   Viresh Kumar <viresh.kumar@...aro.org>
To:     Anson Huang <anson.huang@....com>
Cc:     "robh+dt@...nel.org" <robh+dt@...nel.org>,
        "mark.rutland@....com" <mark.rutland@....com>,
        "shawnguo@...nel.org" <shawnguo@...nel.org>,
        "s.hauer@...gutronix.de" <s.hauer@...gutronix.de>,
        "kernel@...gutronix.de" <kernel@...gutronix.de>,
        "festevam@...il.com" <festevam@...il.com>,
        "catalin.marinas@....com" <catalin.marinas@....com>,
        "will.deacon@....com" <will.deacon@....com>,
        "rjw@...ysocki.net" <rjw@...ysocki.net>,
        Aisheng Dong <aisheng.dong@....com>,
        Daniel Baluta <daniel.baluta@....com>,
        Andy Gross <andy.gross@...aro.org>,
        "horms+renesas@...ge.net.au" <horms+renesas@...ge.net.au>,
        "heiko@...ech.de" <heiko@...ech.de>,
        "arnd@...db.de" <arnd@...db.de>,
        "bjorn.andersson@...aro.org" <bjorn.andersson@...aro.org>,
        "jagan@...rulasolutions.com" <jagan@...rulasolutions.com>,
        "enric.balletbo@...labora.com" <enric.balletbo@...labora.com>,
        "marc.w.gonzalez@...e.fr" <marc.w.gonzalez@...e.fr>,
        "olof@...om.net" <olof@...om.net>,
        "devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
        "linux-arm-kernel@...ts.infradead.org" 
        <linux-arm-kernel@...ts.infradead.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "linux-pm@...r.kernel.org" <linux-pm@...r.kernel.org>,
        dl-linux-imx <linux-imx@....com>
Subject: Re: [PATCH 3/3] cpufreq: imx-sc: add i.mx system controller cpufreq
 support

On 13-02-19, 08:53, Anson Huang wrote:
> Forgot to mention, i.MX system controller cpufreq actually can NOT do any CPU
> clock/voltage scaling from Linux kernel, they are controlled by system controller
> firmware and ONLY can be requested via RPC with secure mode, so Linux kernel
> has to call SMC and trap to ARM-Trusted-Firmware to do it, in this case, is cpufreq-dt
> still suitable to support it? I saw cpufreq-dt driver will do CPU clock/voltage scaling
> directly.

What about moving those SMC calls to the clk-driver, then it wouldn't
matter to the cpufreq driver on how the clock is getting changed.

-- 
viresh