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

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Message-ID: <DB3PR0402MB39161A96602CBF6D38514164F5660@DB3PR0402MB3916.eurprd04.prod.outlook.com>
Date:   Wed, 13 Feb 2019 10:35:32 +0000
From:   Anson Huang <anson.huang@....com>
To:     Viresh Kumar <viresh.kumar@...aro.org>
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



Best Regards!
Anson Huang

> -----Original Message-----
> From: Viresh Kumar [mailto:viresh.kumar@...aro.org]
> Sent: 2019年2月13日 18:15
> To: Anson Huang <anson.huang@....com>
> Cc: robh+dt@...nel.org; mark.rutland@....com; shawnguo@...nel.org;
> s.hauer@...gutronix.de; kernel@...gutronix.de; festevam@...il.com;
> catalin.marinas@....com; will.deacon@....com; rjw@...ysocki.net;
> Aisheng Dong <aisheng.dong@....com>; Daniel Baluta
> <daniel.baluta@....com>; Andy Gross <andy.gross@...aro.org>;
> horms+renesas@...ge.net.au; heiko@...ech.de; arnd@...db.de;
> bjorn.andersson@...aro.org; jagan@...rulasolutions.com;
> enric.balletbo@...labora.com; marc.w.gonzalez@...e.fr; olof@...om.net;
> devicetree@...r.kernel.org; linux-arm-kernel@...ts.infradead.org; linux-
> kernel@...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.

OK, thanks, I will have a try and resend the patch.

Anson.

> 
> --
> viresh