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

Finley Xiao
2016-09-27T08:40:22Z

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

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