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Date:   Wed, 13 Feb 2019 15:42:07 +0530
From:   Viresh Kumar <viresh.kumar@linaro.org>
To:     Anson Huang <anson.huang@nxp.com>
Cc:     "robh+dt@kernel.org" <robh+dt@kernel.org>,
        "mark.rutland@arm.com" <mark.rutland@arm.com>,
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Subject: Re: [PATCH 3/3] cpufreq: imx-sc: add i.mx system controller cpufreq
 support
Message-ID: <20190213101207.ggunz5lhlv46r5o6@vireshk-i7>
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On 13-02-19, 08:46, Anson Huang wrote:
> Hi, Viresh
> 
> Best Regards!
> Anson Huang
> 
> > -----Original Message-----
> > From: Viresh Kumar [mailto:viresh.kumar@linaro.org]
> > Sent: 2019年2月13日 15:09
> > To: Anson Huang <anson.huang@nxp.com>
> > Cc: robh+dt@kernel.org; mark.rutland@arm.com; shawnguo@kernel.org;
> > s.hauer@pengutronix.de; kernel@pengutronix.de; festevam@gmail.com;
> > catalin.marinas@arm.com; will.deacon@arm.com; rjw@rjwysocki.net;
> > Aisheng Dong <aisheng.dong@nxp.com>; Daniel Baluta
> > <daniel.baluta@nxp.com>; Andy Gross <andy.gross@linaro.org>;
> > horms+renesas@verge.net.au; heiko@sntech.de; arnd@arndb.de;
> > bjorn.andersson@linaro.org; jagan@amarulasolutions.com;
> > enric.balletbo@collabora.com; marc.w.gonzalez@free.fr; olof@lixom.net;
> > devicetree@vger.kernel.org; linux-arm-kernel@lists.infradead.org; linux-
> > kernel@vger.kernel.org; linux-pm@vger.kernel.org; dl-linux-imx <linux-
> > imx@nxp.com>
> > Subject: Re: [PATCH 3/3] cpufreq: imx-sc: add i.mx system controller cpufreq
> > support
> > 
> > On 13-02-19, 03:09, Anson Huang wrote:
> > > On NXP's i.MX SoCs with system controller inside, CPU frequency
> > > scaling can ONLY be done by system controller firmware, and it can
> > > ONLY be requested from secure mode, so Linux cpufreq driver has to
> > > call ARM SMC to trap to ARM-Trusted-Firmware to request system
> > > controller firmware to do CPU frequency scaling.
> > >
> > > This patch adds i.MX system controller cpufreq driver support, when
> > > doing CPU frequency scaling, cpufreq driver will do ARM SMC call and
> > > trap to ARM-Trusted-Firmware, then SIP(silicon provider) service will
> > > communicate with system controller for CPU frequenct scaling.
> > >
> > > Signed-off-by: Anson Huang <Anson.Huang@nxp.com>
> > > ---
> > >  drivers/cpufreq/Kconfig.arm      |   9 ++
> > >  drivers/cpufreq/Makefile         |   1 +
> > >  drivers/cpufreq/imx-sc-cpufreq.c | 183
> > > +++++++++++++++++++++++++++++++++++++++
> > >  3 files changed, 193 insertions(+)
> > >  create mode 100644 drivers/cpufreq/imx-sc-cpufreq.c
> > 
> > Why can't you use cpufreq-dt driver like everyone else ?
> 
> Just notice that we can overwrite the set_target if using cpufreq-dt, then we still
> need a platform cpufreq file to implement arch_set_freq_scale(), I can use it to save

Why do you need to implement arch_set_freq_scale() ? It is already
defined for arm64 I believe.

> the code of imx system controller cpufreq driver, and BTW, can cpufreq-dt support
> multi clusters cpufreq? As i.MX8QM has 2 clusters running with different OPPs.

Yes, it supports multi-cluster.

-- 
viresh