[PATCH 01/10] Add a common struct clk

Richard Zhao
2011-04-23T14:08:39Z

On Fri, Apr 22, 2011 at 11:23:49AM +0200, Thomas Gleixner wrote:
> On Fri, 22 Apr 2011, Richard Zhao wrote:
> > Hi Thomas,
> >
> > On Thu, Apr 21, 2011 at 09:48:28PM +0200, Thomas Gleixner wrote:
> > > On Fri, 15 Apr 2011, Sascha Hauer wrote:
> > > > From: Jeremy Kerr <jeremy.kerr@canonical.com>
> > > > + * @get: Called by the core clock code when a device driver acquires a
> > > > + * clock via clk_get(). Optional.
> > > > + *
> > > > + * @put: Called by the core clock code when a devices driver releases a
> > > > + * clock via clk_put(). Optional.
> > >
> > > These callbacks are completely pointless. There are only two non empty
> > > implementations in tree:
> > >
> > > One does a try_module_get(clk->owner), which should be done in generic
> > > code. The other does special clock enabling magic which wants to go to
> > > clk->prepare().
> > You forget mach-u300 __clk_get. It updates some registers.
> > The ops get/put let arch clock driver have a chance to do special things at the
> > time when a user begins to use the clock.
>
> No I did not forget. It's exactly the code which wants to go into
> clk->prepare. Which you have to call _before_ doing anything with the
> clock, so there is no need for an extra callback.
No. clk_prepare only have to be called before clk_enable, but not have to for
other operations, set_rate/set_parent etc.

Thanks
Richard
>
> Thanks,
>
> tglx