linux-kernel - Re: [PATCH v2 4/4] PM / AVS: rockchip-cpu-avs: add driver handling Rockchip cpu avs

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Date:   Tue, 27 Sep 2016 16:40:22 +0800
From:   Finley Xiao <finley.xiao@...k-chips.com>
To:     Heiko Stuebner <heiko@...ech.de>,
        Viresh Kumar <viresh.kumar@...aro.org>,
        Stephen Boyd <sboyd@...eaurora.org>
Cc:     srinivas.kandagatla@...aro.org, maxime.ripard@...e-electrons.com,
        robh+dt@...nel.org, frowand.list@...il.com, sre@...nel.org,
        dbaryshkov@...il.com, dwmw2@...radead.org, mark.rutland@....com,
        khilman@...nel.org, nm@...com, rjw@...ysocki.net,
        linux-arm-kernel@...ts.infradead.org,
        linux-rockchip@...ts.infradead.org, devicetree@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-pm@...r.kernel.org,
        wxt@...k-chips.com, jay.xu@...k-chips.com,
        rocky.hao@...k-chips.com, tim.chen@...k-chips.com,
        tony.xie@...k-chips.com, ulysses.huang@...k-chips.com,
        lin.huang@...k-chips.com
Subject: Re: [PATCH v2 4/4] PM / AVS: rockchip-cpu-avs: add driver handling
 Rockchip cpu avs



在 2016/9/26 16:05, Heiko Stuebner 写道:
> Am Montag, 26. September 2016, 09:25:11 CEST schrieb Viresh Kumar:
>> On 12-09-16, 14:55, Stephen Boyd wrote:
>>> On 08/29, Viresh Kumar wrote:
>>>> On 18-08-16, 16:52, Finlye Xiao wrote:
>>>>> +static int rockchip_adjust_opp_table(struct device *cpu_dev,
>>>>> +				     struct cpufreq_frequency_table *table,
>>>>> +				     int volt)
>>>>> +{
>>>>> +	struct opp_table *opp_table;
>>>>> +	struct cpufreq_frequency_table *pos;
>>>>> +	struct dev_pm_opp *opp;
>>>>> +
>>>>> +	if (!volt)
>>>>> +		return 0;
>>>>> +
>>>>> +	rcu_read_lock();
>>>>> +
>>>>> +	opp_table = _find_opp_table(cpu_dev);
>>>>> +	if (IS_ERR(opp_table)) {
>>>>> +		rcu_read_unlock();
>>>>> +		return PTR_ERR(opp_table);
>>>>> +	}
>>>>> +
>>>>> +	cpufreq_for_each_valid_entry(pos, table) {
>>>>> +		opp = dev_pm_opp_find_freq_exact(cpu_dev, pos->frequency * 1000,
>>>>> +						 true);
>>>>> +		if (IS_ERR(opp))
>>>>> +			continue;
>>>>> +
>>>>> +		opp->u_volt += volt;
>>>>> +		opp->u_volt_min += volt;
>>>>> +		opp->u_volt_max += volt;
>>>>> +	}
>>>>> +
>>>>> +	rcu_read_unlock();
>>>>> +
>>>>> +	return 0;
>>>>> +}
>>>> I wouldn't prefer altering the opp tables from individual drivers at
>>>> all. At the least, it should be done via some helpers exposed by the
>>>> core.
>>>>
>>>> But before that I would like to hear from Stephen a bit as I recall he
>>>> was also working on something similar.
>>> I had a patch to modify the voltage at runtime for the "current"
>>> OPP. Now that we have regulator and clk control inside OPP that
>>> became a little easier to do without having to do some notifier
>>> from the OPP layer to the consumers. I haven't had time to revive
>>> those patches though. Should we do that?
>> Perhaps yes, we should have a common place for doing all that.
>>
>>> Does this need to modify
>>> anything besides the OPP the device is currently running at?
>> Finlye, can you please answer this ?
> If I understand it correctly, depending on the leakage value stored in an
> efuse, all opp voltages are reduced by a certain value. Right now the driver
> does it in one go for the full opp table, but of course could also do it for
> each new opp individually before it gets set.
>
Yes， it is necessary to modify all opp voltages and  I agreed with Heiko.
>

-- 
Finley