[RFC 1/1] clk: Add notifier support in clk_prepare_enable/clk_disable_unprepare

[Peter De Schrijver]

On Thu, Mar 14, 2013 at 03:15:11AM +0100, Bill Huang wrote:

> I don't think deferring will work either, considering the usage of DVFS,
> device voltage is tightly coupled with frequency, when clock rate is
> about to increase, we have to boost voltage first and we can lower the
> voltage after the clock rate has decreased. All the above sequence have
> to be guaranteed or you might crash, so deferring not only make thing
> complicated in controlling the order but also hurt performance.

But we could use notifiers in clk_prepare/clk_unprepare to set the voltage no?
As clk_prepare/clk_unprepare have to be called before clk_enable or after
clk_disable, the voltage can be raised to a safe level, before the clock
becomes active.

Cheers,

Peter.