Re: [PATCH] arm64: dts: allwinner: a64: Drop PMU node

Harald Geyer
2019-08-06T20:24:59Z

Vasily Khoruzhick writes:
> On Tue, Aug 6, 2019 at 7:35 AM Robin Murphy <robin.murphy@arm.com> wrote:
> >
> > On 06/08/2019 15:01, Vasily Khoruzhick wrote:
> > > Looks like PMU in A64 is broken, it generates no interrupts at all and
> > > as result 'perf top' shows no events.
> >
> > Does something like 'perf stat sleep 1' at least count cycles correctly?
> > It could well just be that the interrupt numbers are wrong...
>
> Looks like it does, at least result looks plausible:

I'm using perf stat regularly (cache benchmarks) and it works fine.

Unfortunately I wasn't aware that perf stat is a poor test for
the interrupts part of the node, when I added it. So I'm not too
surprised I got it wrong.

However, it would be unfortunate if the node got removed completely,
because perf stat would not work anymore. Maybe we can only remove
the interrupts or just fix them even if the HW doesn't work?

Harald