On Tue, May 7, 2019 at 4:05 AM Lukasz Luba <l.luba@xxxxxxxxxxxxxxxxxxx> wrote: > > Hi Rob, > > On 5/6/19 12:29 PM, Lukasz Luba wrote: > > Hi Rob, > > > > On 5/2/19 10:24 PM, Rob Herring wrote: > >> On Thu, May 2, 2019 at 3:52 AM Lukasz Luba > >> <l.luba@xxxxxxxxxxxxxxxxxxx> wrote: > >>> > >>> Hi Rob, > >>> > >>> On 5/1/19 12:36 AM, Rob Herring wrote: > >>>> On Fri, Apr 19, 2019 at 03:48:07PM +0200, Lukasz Luba wrote: > >>>>> Extend the documenation by events description with new > >>>>> 'event-data-type' > >>>>> field. Add example how the event might be defined in DT. > >>>> > >>>> Why do we need event types in DT? We don't do this for other h/w > >>>> such as > >>>> ARM PMU. > >>> In ARM PMU all the events are hard-coded into the driver code i.e. in v7 > >>> arch/arm/kernel/perf_event_v7.c > >>> and are seen from perf. They are different type and for different > >>> purpose. The Ecynos PPMU events are not seen in perf, they are > >>> for internal monitoring and must not be reset by other actors like perf. > >>> They are used by the 'bus drivers' to made some heuristics and tune the > >>> internal settings, like frequency. > >>> > >>> Chanwoo has written PPMU driver which relies on DT definition. > >>> The DT events are used by other DT devices by phandle. > >> > >> How is that done? I don't see anything in the binding for that. > > Here are the DT devices and how they are pinned together: > > - declared devfreq events: > > https://elixir.bootlin.com/linux/latest/source/arch/arm/boot/dts/exynos4412-ppmu-common.dtsi > > > > - devfreq events pinned to the bus device: > > https://elixir.bootlin.com/linux/latest/source/arch/arm/boot/dts/exynos4412-odroid-common.dtsi#L107 > > > > - the bus device itself: > > https://elixir.bootlin.com/linux/latest/source/arch/arm/boot/dts/exynos4412.dtsi#L457 > > > > > > Regards, > > Lukasz > > > >> > >> Rob > >> > >> > Can I send the next version of the patch set, which has Chanwoo's > suggestions, or do you have some objections to this PPMU entries? I think the existing binding which this is based on needs some changes, so it's pointless really for me to comment on additions. Rob
