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From:   Leonard Crestez <leonard.crestez@nxp.com>
To:     Anson Huang <anson.huang@nxp.com>,
        "viresh.kumar@linaro.org" <viresh.kumar@linaro.org>
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        <linux-arm-kernel@lists.infradead.org>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        dl-linux-imx <linux-imx@nxp.com>,
        Lucas Stach <l.stach@pengutronix.de>
Subject: Re: [PATCH] cpufreq: imx-cpufreq-dt: Assign max supported frequency
 as suspend frequency
Thread-Topic: [PATCH] cpufreq: imx-cpufreq-dt: Assign max supported frequency
 as suspend frequency
Thread-Index: AQHVNWKKfVJcms96j06437RrlyrVzA==
Date:   Mon, 8 Jul 2019 11:04:01 +0000
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References: <20190708074624.910-1-Anson.Huang@nxp.com>
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On 7/8/2019 10:55 AM, Anson.Huang@nxp.com wrote:=0A=
> To reduce the suspend/resume latency, CPU's max supported frequency=0A=
> should be used during low level suspend/resume phase, "opp-suspend"=0A=
> property is NOT feasible since OPP defined in DT could be NOT supported=
=0A=
> according to speed garding and market segment fuse settings. So we=0A=
> can assign the cpufreq policy's suspend_freq with max available=0A=
> frequency provided by cpufreq driver.=0A=
> =0A=
> Signed-off-by: Anson Huang <Anson.Huang@nxp.com>=0A=
=0A=
> diff --git a/drivers/cpufreq/imx-cpufreq-dt.c b/drivers/cpufreq/imx-cpufr=
eq-dt.c=0A=
=0A=
> +static int __init imx_cpufreq_dt_setup_suspend_opp(void)=0A=
> +{=0A=
> +	struct cpufreq_policy *policy =3D cpufreq_cpu_get(0);=0A=
> +=0A=
> +	policy->suspend_freq =3D cpufreq_quick_get_max(0);=0A=
> +=0A=
> +	return 0;=0A=
> +}=0A=
> +late_initcall(imx_cpufreq_dt_setup_suspend_opp);=0A=
=0A=
The imx-cpufreq-dt driver is built as a module by default and this patch =
=0A=
produces an error:=0A=
=0A=
In file included from ../drivers/cpufreq/imx-cpufreq-dt.c:11:=0A=
../include/linux/module.h:131:42: error: redefinition of =91__inittest=92=
=0A=
   static inline initcall_t __maybe_unused __inittest(void)  \=0A=
                                           ^~~~~~~~~~=0A=
../include/linux/device.h:1656:1: note: in expansion of macro =91module_ini=
t=92=0A=
  module_init(__driver##_init); \=0A=
  ^~~~~~~~~~~=0A=
=0A=
As far as I can tell late_initcall is not supported for modules.=0A=
=0A=
Viresh: "max freq as suspend freq" is something that could be useful for =
=0A=
other SOC families. The hardware can suspend at any freq; it's just that =
=0A=
the highest one makes sense because it makes suspend/resume slightly faster=
.=0A=
=0A=
Could this behavior be pushed to cpufreq-dt as a bool flag inside struct =
=0A=
cpufreq_dt_platform_data?=0A=
=0A=
Only a few other platforms use this, most others pass NULL like imx. But =
=0A=
passing custom SOC-specific flags to cpufreq-dt makes a lot of sense=0A=
=0A=
--=0A=
Regards,=0A=
Leonard=0A=
=0A=