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

[Finley Xiao]

å 2016/9/26 16:05, Heiko Stuebner åé:
> 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.
Yesï it is necessary to modify all opp voltages and  I agreed with Heiko.
>

--
Finley