On 03/14/2013 03:28 AM, Bill Huang wrote: > On Thu, 2013-03-14 at 17:21 +0800, Peter De Schrijver wrote: >> On Thu, Mar 14, 2013 at 03:15:11AM +0100, Bill Huang wrote: >> >>> I don't think deferring will work either, considering the usage of DVFS, >>> device voltage is tightly coupled with frequency, when clock rate is >>> about to increase, we have to boost voltage first and we can lower the >>> voltage after the clock rate has decreased. All the above sequence have >>> to be guaranteed or you might crash, so deferring not only make thing >>> complicated in controlling the order but also hurt performance. >> >> But we could use notifiers in clk_prepare/clk_unprepare to set the voltage >> no? >> As clk_prepare/clk_unprepare have to be called before clk_enable or after >> clk_disable, the voltage can be raised to a safe level, before the clock >> becomes active. > > Thanks Peter, actually I'm just about to propose my v2 RFC which add > notifier in clk_prepare/clk_unprepare.
Can't clk_set_rate() be called while the clock is prepared, or even enabled? I don't see how your proposal would work. -- 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/
