Re: [PATCH 2/5] clk: notifier handler for dynamic voltage scaling

Bill Huang
2013-03-01T09:30:54Z

On Thu, 2013-02-28 at 12:49 +0800, Mike Turquette wrote:
> Dynamic voltage and frequency scaling (dvfs) is a common power saving
> technique in many of today's modern processors. This patch introduces a
> common clk rate-change notifier handler which scales voltage
> appropriately whenever clk_set_rate is called on an affected clock.

I really think clk_enable and clk_disable should also be triggering
notifier call and DVFS should act accordingly since there are cases
drivers won't set clock rate but instead disable its clock directly, do
you agree?
>
> There are three prerequisites to using this feature:
>
> 1) the affected clocks must be using the common clk framework
> 2) voltage must be scaled using the regulator framework
> 3) clock frequency and regulator voltage values must be paired via the
> OPP library

Just a note, Tegra Core won't meet prerequisite #3 since each regulator
voltage values is associated with clocks driving those many sub-HW
blocks in it.