Messages in this thread | | | From | Jeremy Kerr <> | Subject | Re: [RFC,PATCH 1/3] Add a common struct clk | Date | Tue, 15 Feb 2011 09:36:25 +0800 |
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Hi 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); ?
Added later, but yes.
> > > + 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?
It does, yes. Driver code should be always be calling clk_enable before using a clock, regardless of the implementation (which it shouldn't have to care abut), and should abort their initialisation if the clk_enable() fails.
Some clocks are always running, so the enable op will be empty. This is not an error, so the driver is free to continue.
> 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.
Sounds like useless boilerplate - it's not an error to not need enable/disable, so I don't see why we need to add extra effort to handle this case.
> > +/** > > + * __clk_get - acquire a reference to a clock > > + * > > + * @clk: The clock to refcount > > + * > > + * Before a clock is returned from clk_get, this function should be > > called + * to update any clock-specific refcounting. > > This is a bit misleading. It's not "should be called", it "is called". I > think you should just remove the documentation for __clk_get/__clk_put > or move it into clk.c since the functions are only used internally by > the common clock code.
It'd be nice to remove this from the header, but this means we'll need extern prototypes in clkdev.c. Might be a reasonable compromise though.
> > +/** > > + * clk_prepare - prepare clock for atomic enabling. > > + * > > + * @clk: The clock to prepare > > + * > > + * Do any blocking initialisation on @clk, allowing the clock to be > > later + * enabled atomically (via clk_enable). This function may sleep. > > "Possibly blocking" as below?
Yep, will unify these (and spell "possibly" correctly :) )
Cheers,
Jeremy
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