Re: [PATCH V2] cpufreq: Make sure CPU is running on a freq from freq-table

[Viresh Kumar]

On 25 November 2013 22:08, Dirk Brandewie <dirk.brandewie@xxxxxxxxx> wrote:
> IMHO this issue should be fixed in the scaling driver for the platform.
>
> The scaling driver sets policy->cur and fills in the frequency table and has

Not anymore, policy->cur is set in the core for most of the drivers now.
Drivers just provide ->get() callbacks.

> the ability to adjust the frequency of the CPU.

I believe this kind of decisions should stay with the core, drivers should
just provide the backend instead of intelligence..

> Letting this leak up into the core
> is wrong IMHO and just widens the window where the CPU will be running at
> the wrong frequency set by the bootloader.

It doesn't stay there for long enough.. we get to this point in
cpufreq core just
after calling ->init(), and if the CPU is working without issues until
now, it will
stay stable for few more milliseconds.

> Shouldn't there be a check to see if the problem exists at all?  Otherwise
> the core is setting a policy for ALL platform even those where the issue
> does
> not exist.

That is taken care of by __cpufreq_driver_target(). It checks if we are
already running at requested frequency or not (after getting the next
higher frequency)... If current freq is present in table,
cpufreq_frequency_table_target() will return current frequency only for
policy->cur -1. And so we will not end up configuring hardware
unnecessarily.
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