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

Vasily Khoruzhick
2019-08-06T20:52:41Z

On Tue, Aug 6, 2019 at 1:19 PM Harald Geyer <harald@ccbib.org> wrote:
>
> 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?

I'm not familiar with PMU driver. Is it possible to get it working
without interrupts?

>
> Harald