Is cpufreq-dt safe without regulator support?

[Viresh Kumar]

On 17 March 2015 at 13:15, wens Tsai <wens213 at gmail.com> wrote:
> The sunxi platform added cpufreq support in 4.0.0-rc1 using
> the generic cpufreq-dt driver. One issue we've run into is
> the default OPPs we use include an overclocked/overvoltage
> setting.

There is a feature for that in cpufreq, in case you don't know, "boost"..

> If the cpu is missing a regulator supply phandle, or the
> kernel is built without regulators, cpufreq can increase
> the clock rate without the needed voltage increase.

Right.

> The former issue can be resolved by providing a dummy
> regulator with the default voltage, effectively disabling
> cpufreq.

How ? CPUFreq will try to change both volt and freq. Volt
wouldn't change as its a dummy regulator, but freq would
still be changed..

> The latter is possible. Without regulator support built-in,
> even a correct, complete DTS can still fail. Should I just
> remove the offending OPP? Still that does not fix the
> problem when we actually do want overclocking.
>
> To summarize, should cpufreq-dt probe fail when regulator
> support isn't available? Should we differentiate between

No. We can have regulator support enabled but no regulator
for a CPU. And so the current state of code looks fine.

> not having a regulator phandle vs no regulator support?

What I couldn't understand is, why would you miss the regulator
phandle in dts? Or not compile regulator support?

In case you want cpufreq-dt to be disabled if regulators aren't
compiled in, then what you should do is, don't create the platform
device required for probing cpufreq-dt driver.