linux-kernel - RE: [PATCH v10 1/2] cpufreq: Add Kryo CPU scaling driver

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Date:   Wed, 23 May 2018 14:06:24 +0300
From:   <ilialin@...eaurora.org>
To:     "'Sudeep Holla'" <sudeep.holla@....com>
Cc:     <vireshk@...nel.org>, <nm@...com>, <sboyd@...nel.org>,
        <robh@...nel.org>, <mark.rutland@....com>, <rjw@...ysocki.net>,
        <linux-pm@...r.kernel.org>, <devicetree@...r.kernel.org>,
        <linux-kernel@...r.kernel.org>
Subject: RE: [PATCH v10 1/2] cpufreq: Add Kryo CPU scaling driver



> -----Original Message-----
> From: Sudeep Holla <sudeep.holla@....com>
> Sent: Wednesday, May 23, 2018 13:40
> To: Ilia Lin <ilialin@...eaurora.org>; vireshk@...nel.org; nm@...com;
> sboyd@...nel.org; robh@...nel.org; mark.rutland@....com;
> rjw@...ysocki.net; linux-pm@...r.kernel.org; devicetree@...r.kernel.org;
> linux-kernel@...r.kernel.org
> Cc: Sudeep Holla <sudeep.holla@....com>
> Subject: Re: [PATCH v10 1/2] cpufreq: Add Kryo CPU scaling driver
> 
> 
> 
> On 23/05/18 10:40, Ilia Lin wrote:
> > In Certain QCOM SoCs like apq8096 and msm8996 that have KRYO
> > processors, the CPU frequency subset and voltage value of each OPP
> > varies based on the silicon variant in use. Qualcomm Process Voltage
> > Scaling Tables defines the voltage and frequency value based on the
> > msm-id in SMEM and speedbin blown in the efuse combination.
> > The qcom-cpufreq-kryo driver reads the msm-id and efuse value from the
> > SoC to provide the OPP framework with required information.
> > This is used to determine the voltage and frequency value for each OPP
> > of
> > operating-points-v2 table when it is parsed by the OPP framework.
> >
> > Signed-off-by: Ilia Lin <ilialin@...eaurora.org>
> 
> [...]
> 
> > +	pdev = platform_device_register_simple("cpufreq-dt", -1, NULL, 0);
> > +	if (!IS_ERR(pdev))
> > +		return 0;
> > +
> > +	ret = PTR_ERR(pdev);
> > +	dev_err(cpu_dev, "Failed to register platform device\n");
> > +
> > +free_opp:
> > +	for_each_possible_cpu(cpu) {
> > +		if (IS_ERR_OR_NULL(opp_tables[cpu]))
> > +			break;
> > +		dev_pm_opp_put_supported_hw(opp_tables[cpu]);
> > +	}
> > +free_np:
> > +	of_node_put(np);
> > +
> > +	return ret;
> > +}
> > +late_initcall(qcom_cpufreq_kryo_driver_init);
> 
> Any particular reason why this *has* to be late initcall ?
> Please change it to module_initcall otherwise.

The purpose is to give the cpufreq-dt the time to register the driver and only then my driver will add the platform device.

> Also address the of_node comments from Viresh.
> 
> Otherwise, it looks good.
> --
> Regards,
> Sudeep