linux-kernel - Re: [PATCH] cpufreq: Add Kryo CPU scaling driver

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Date:   Wed, 23 May 2018 11:14:05 +0530
From:   Viresh Kumar <viresh.kumar@...aro.org>
To:     Sudeep Holla <sudeep.holla@....com>
Cc:     Ilia Lin <ilialin@...eaurora.org>, linux-clk@...r.kernel.org,
        devicetree@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-pm@...r.kernel.org, linux-arm-msm@...r.kernel.org,
        linux-soc@...r.kernel.org, linux-arm-kernel@...ts.infradead.org
Subject: Re: [PATCH] cpufreq: Add Kryo CPU scaling driver

On 22-05-18, 14:07, Sudeep Holla wrote:
> On Tue, May 22, 2018 at 02:29:45PM +0300, 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>
> > Acked-by: Viresh Kumar <viresh.kumar@...aro.org>
> 
> [...]
> 
> > +
> > +	switch (msm8996_version) {
> > +	case MSM8996_V3:
> > +		versions = 1 << (unsigned int)(*speedbin);
> > +		break;
> > +	case MSM8996_SG:
> > +		versions = 1 << ((unsigned int)(*speedbin) + 4);
> > +		break;
> > +	default:
> > +		BUG();
> > +		break;
> > +	}
> > +
> > +	for_each_possible_cpu(cpu) {
> > +		cpu_dev = get_cpu_device(cpu);
> > +		if (NULL == cpu_dev) {
> > +			ret = -ENODEV;
> > +			goto free_opp;
> > +		}
> > +
> > +		opp_tables[cpu] = dev_pm_opp_set_supported_hw(cpu_dev,
> > +							      &versions, 1);
> 
> Will be not get NULL for all CPUs except 0 ?

With my patches, we will get the OPP table again with refcount
incremented. And on failures, we need to call put-supported-hw helper
only for the CPUs for which it passed previously.

-- 
viresh