Re: [PATCH B 04/10] OMAP3 PRCM: add DPLL1-5 powerdomains, clockdomains; mark clocks

From: Russell King - ARM Linux
Date: Sat Jan 31 2009 - 09:18:01 EST


On Tue, Jan 27, 2009 at 07:44:18PM -0700, Paul Walmsley wrote:
> Each DPLL exists in its own powerdomain (cf 34xx TRM figure 4-18) and
> clockdomain; so, create powerdomain and clockdomain structures for them.
> Mark each DPLL clock as belonging to their respective DPLL clockdomain.
> cf. 34xx TRM Table 4-27 (among other references).

I don't really see the need to mark all these clocks as having a domain.
Yes, it makes sense to mark the actual DPLL clocks themselves with the
relevent DPLL domain. However, it makes no sense to mark the children
as well.

Why? When we enable a clock, we walk up the tree enabling the domains
first. So, even if we're enabling a child clock, we will walk the tree
up to the DPLL and enable the clock domain before we do anything at all.

Sure, if a clock has a multiplexer and that multiplexer is in a different
clock domain from its parent, it makes sense to. But otherwise it doesn't.
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