Re: [v2 1/4] ARM: tegra20: create a DT header defining CLK IDs

[Peter De Schrijver <pdeschrijver@nvidia.com>]

On Fri, Feb 15, 2013 at 05:45:45PM +0100, Stephen Warren wrote:

...

> > I would suggest removing this clock. It's not actually implemented in the CCF
> > and rather useless. If you would gate the CPU clock from the CPU by writing to
> > this register, how would you ungate it? :) Note that this would gate the clock
> > to all CPUs.
> 
> (Note that my comment was re: all clocks, not just that one clock)
> 
> Can't the PMC or flow-controller ungate the clock based on some event?

I don't think the flow-controller controls this gate. The usual way of
clockgating a core is to execute a WFI instruction. That will trigger
clockgating the core, unless the flow-controller has been programmed to do
something else. The flow-controller will ungate the clock when there is an
interrupt.

> Either way, that clock definition exists in HW, right? So I don't think
> there's actually any harm in including the definition in the binding
> even if we never implement/use it.

The clock definition seems to exist in HW yes, the corresponding resetbit
however is marked as 'reserved' in the Tegra114 documentation.

Cheers,

Peter.