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. Rob
