Messages in this thread | | | Date | Thu, 10 Feb 2011 21:08:00 +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 11:46:39AM +0100, Uwe Kleine-König wrote: > Hello, > > On Thu, Feb 10, 2011 at 06:03:19PM +0800, 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 > > set_rate: fail > > get_rate: reture parent's get_rate > > set_parent: fail > > get_parent: fail > I wouldn't hard-code the parents into the generic functions. But I > suggest to provide generic callbacks to do this, e.g. Why? what restriction will it cause to add parent in clk? Two benifits at least I can see: 1. null ops handle, as I said above. 2. export clock tree to user level for debug. It's very helpfull.
Thanks Richard > > clk_get_rate_from_parent(struct clk *c) > { > struct clk *parent = clk_get_parent(c); > > return clk_get_rate(parent); > } > > Best regards > Uwe > > -- > Pengutronix e.K. | Uwe Kleine-König | > Industrial Linux Solutions | http://www.pengutronix.de/ | > > _______________________________________________ > linux-arm-kernel mailing list > linux-arm-kernel@lists.infradead.org > http://lists.infradead.org/mailman/listinfo/linux-arm-kernel -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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