Messages in this thread | | | Date | Thu, 10 Feb 2011 20:45:43 +0800 | From | Richard Zhao <> | Subject | Re: [RFC,PATCH 1/3] Add a common struct clk |
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On Thu, Feb 10, 2011 at 11:10:52PM +1300, Ryan Mallon wrote: > 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? I mean prepare/unprepare, enable/disable and get_rate ops null can be handled in the common clock code. But it needs parent clock pointer.
Thanks Richard > > ~Ryan > > _______________________________________________ > linux-arm-kernel mailing list > linux-arm-kernel@lists.infradead.org > http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
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