On 11/01/11 11:15, Richard Zhao wrote:

2011/1/11 Uwe Kleine-K?nig [off-list ref]:

[snip]

A well running board will not enable/disable PLLs frequently. It don't
make sense. PLLs are normally disabled on request to enter low power
mode, rather not because all their child clocks are disabled.   So we
don't have to consider the time here.

I'd rather see that if all child clocks are disabled the PLL is
powered down then. It means PLLs _could_ be left running even
when power-down mode is selected because the system still thinks
that a peripheral is using them.

If you want to make it so that each low-power mode has to work
out what PLLs need to be disabled and then re-enabled makes me
want to be sick. Hiding this stuff behind specific implementations
is a recipe for disaster.