Hi Thomas, On Mon, Sep 6, 2010 at 2:00 PM, Thomas Renninger <trenn@xxxxxxx> wrote: > On Monday 06 September 2010 13:27:13 Jean Pihet wrote: >> On Mon, Sep 6, 2010 at 12:42 PM, Thomas Renninger <trenn@xxxxxxx> wrote: > ... >> In order to reach an efficient low power mode you >> need to ensure that all clocks in a clock domain are idled or cut off >> (automatically by the HW or with the intervention of SW drivers). >> >> The HW complexity requires the tracing of all those clocks/power >> states, that is why new events are proposed. > Hm, but if the HW can switch clocks behind your back, how do you > realize that to throw a perf clock power event then? Such clocks are automatically shut off when there is no activity on the module, this allows the system to reach a lower power state. All that is needed is to ensure the modules are correctly configured to shut off unneeded clocks automatically. > Theoretically you need to poll to keep track of HW switching the > clocks? No. I would not poll hundreds of clocks. Furthermore there is no event to be thrown away, in the case the reached power mode is not 'deep' enough you need a trace point showing what blocked the transition. There is still work to do to achieve that, it is coming soon. > > Thomas > Note: a re-spin of the patch has been sent on a new thread. Jean _______________________________________________ linux-pm mailing list linux-pm@xxxxxxxxxxxxxxxxxxxxxxxxxx https://lists.linux-foundation.org/mailman/listinfo/linux-pm
