Re: [RFC,PATCH 1/3] Add a common struct clk

[Ryan Mallon]

On 10/02/11 23:03, Richard Zhao wrote:
> On Thu, Feb 10, 2011 at 09:21:14AM +1300, Ryan Mallon wrote:
> > On 02/09/2011 07:41 PM, Jeremy Kerr wrote:
> >
> > Hi Jeremy,
> >
> > Couple more comments below.
> >
> > ~Ryan
> [...]
> > > +int clk_enable(struct clk *clk)
> > > +{
> > > +     unsigned long flags;
> > > +     int ret = 0;
> > > +
> > > +     spin_lock_irqsave(&clk->enable_lock, flags);
> >          WARN_ON(clk->prepare_count == 0); ?
> >
> > > +     if (clk->enable_count == 0&&  clk->ops->enable)
> > > +             ret = clk->ops->enable(clk);
> > Does it make sense to have a clock with no enable function which still
> > returns success from clk_enable? Do we have any platforms which have
> > NULL clk_enable functions?
> >
> > I think that for enable/disable at least we should require platforms to
> > provide functions and oops if they have failed to do so. In the rare
> > case that a platform doesn't need to do anything for enable/disable they
> > can just supply empty functions.
> It's possible to be NULL. So are set_rate/get_rate.
> Ideally, if it's NULL:
> prepare/unprepare: only call parent's prepare/unprepare
> enable/disable: only call parent's enable/disable

No, the whole point of the generic framework is that _all_ clock users 
must call prepare/enable and disable/unprepare. Drivers, etc should not 
rely on underlying knowledge of a platform. This is why, for instance, 
clk_enable will warn if prepare count is zero.

However, I can see that a clock may be fully enabled by its prepare 
function and so the enable function is a no-op. User must still call 
both prepare and enable though. Perhaps this is what you meant?

~Ryan
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