On Fri, 15 Mar 2013, Russell King - ARM Linux wrote: > On Tue, Mar 12, 2013 at 06:47:53PM -0700, Bill Huang wrote: > > On Tue, 2013-03-12 at 21:40 +0800, Russell King - ARM Linux wrote: > > > On Tue, Mar 12, 2013 at 05:37:41AM -0700, Bill Huang wrote: > > > > Add the below four notifier events so drivers which are interested in > > > > knowing the clock status can act accordingly. This is extremely useful > > > > in some of the DVFS (Dynamic Voltage Frequency Scaling) design. > > > > > > > > PRE_CLK_ENABLE > > > > POST_CLK_ENABLE > > > > PRE_CLK_DISABLE > > > > POST_CLK_DISABLE > > > > > > > > Signed-off-by: Bill Huang <bilhu...@nvidia.com> > > > > > > NAK. *Sigh* NO, this is the wrong level to be doing stuff like this. > > > > > > The *ONLY* thing that clk_prepare_enable() and clk_prepare_disable() > > > should > > > *EVER* be doing is calling clk_prepare(), clk_enable(), clk_disable() and > > > clk_unprepare(). Those two functions are *merely* helpers for drivers > > > who don't wish to make the individual calls. > > > > > > Drivers are still completely free to call the individual functions, at > > > which point your proposal breaks horribly - and they _do_ call the > > > individual functions. > > > > I'm proposing to give device driver a choice when it knows that some > > driver might be interested in knowing its clock's enabled/disabled state > > change at runtime, this is very important for centralized DVFS core > > driver. It is not meant to be covering all cases especially for drivers > > which is not part of the DVFS, so we don't care if it is calling > > clk_enable/disable directly or not. > > But you're not giving drivers a choice. You're giving them an ultimatum. > Either they use clk_prepare_enable() which must only be called from non- > atomic contexts and have the notifiers, or if they need to use the > individual functions (which is what they _should_ be doing but people > are too lazy to properly convert stuff) they don't get the option of > the notifiers at all. > > This sucks totally, design wise. > > The whole point of clk_prepare_enable() is that it is a helper function > to _only_ do the clk_prepare() call followed by a clk_enable() call and > _nothing_ _else_ _what_ _so_ _ever_.
If people are too lazy and start abusing clk_prepare_enable() then this helper function becomes counter-productive and should simply be removed. Same issue as with IS_ERR_OR_NULL(). Nicolas -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/