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List:       devicetree
Subject:    Re: [PATCH] arm64: dts: allwinner: a64: Drop PMU node
From:       Vasily Khoruzhick <anarsoul () gmail ! com>
Date:       2019-10-31 20:35:40
Message-ID: CA+E=qVeopby6zn1PBsOGb0JjA6-viTN_iXxRnWF6+NGtbZ_BtQ () mail ! gmail ! com
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On Thu, Oct 31, 2019 at 12:10 PM Cl=C3=A9ment P=C3=A9ron <peron.clem@gmail.=
com> wrote:
>
> Hi,
>
> Just a remark here but the interrupt are from 152 to 155 SPI.
> But there is an offset of 32 no (remove SGI/PPI)?
> This should be from 120 to 123

I already tried it (and I believe someone already suggested it above),
it doesn't fix PMU interrupts though.

> Regards,
> Cl=C3=A9ment
>
> On Wed, 25 Sep 2019 at 13:09, Maxime Ripard <mripard@kernel.org> wrote:
> >
> > On Mon, Sep 23, 2019 at 04:55:59PM -0700, Vasily Khoruzhick wrote:
> > > On Mon, Sep 23, 2019 at 4:51 PM Vasily Khoruzhick <anarsoul@gmail.com=
> wrote:
> > > >
> > > > On Mon, Aug 12, 2019 at 10:39 PM Maxime Ripard
> > > > <maxime.ripard@bootlin.com> wrote:
> > > > >
> > > > > On Mon, Aug 12, 2019 at 11:01:51AM -0700, Vasily Khoruzhick wrote=
:
> > > > > > On Mon, Aug 12, 2019 at 1:04 AM Maxime Ripard <maxime.ripard@bo=
otlin.com> wrote:
> > > > > > >
> > > > > > > On Thu, Aug 08, 2019 at 12:59:07PM -0700, Vasily Khoruzhick w=
rote:
> > > > > > > > On Thu, Aug 8, 2019 at 9:26 AM Maxime Ripard <maxime.ripard=
@bootlin.com> wrote:
> > > > > > > > >
> > > > > > > > > On Wed, Aug 07, 2019 at 10:36:08AM -0700, Vasily Khoruzhi=
ck wrote:
> > > > > > > > > > On Wed, Aug 7, 2019 at 4:56 AM Maxime Ripard <maxime.ri=
pard@bootlin.com> wrote:
> > > > > > > > > > >
> > > > > > > > > > > On Tue, Aug 06, 2019 at 07:39:26PM -0700, Vasily Khor=
uzhick wrote:
> > > > > > > > > > > > On Tue, Aug 6, 2019 at 2:14 PM Robin Murphy <robin.=
murphy@arm.com> wrote:
> > > > > > > > > > > > >
> > > > > > > > > > > > > On 2019-08-06 9:52 pm, Vasily Khoruzhick wrote:
> > > > > > > > > > > > > > On Tue, Aug 6, 2019 at 1:19 PM Harald Geyer <ha=
rald@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 generat=
es no interrupts at all and
> > > > > > > > > > > > > >>>>> as result 'perf top' shows no events.
> > > > > > > > > > > > > >>>>
> > > > > > > > > > > > > >>>> Does something like 'perf stat sleep 1' at l=
east count cycles correctly?
> > > > > > > > > > > > > >>>> It could well just be that the interrupt num=
bers are wrong...
> > > > > > > > > > > > > >>>
> > > > > > > > > > > > > >>> Looks like it does, at least result looks pla=
usible:
> > > > > > > > > > > > > >>
> > > > > > > > > > > > > >> I'm using perf stat regularly (cache benchmark=
s) 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 g=
ot removed completely,
> > > > > > > > > > > > > >> because perf stat would not work anymore. Mayb=
e 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 possibl=
e to get it working
> > > > > > > > > > > > > > without interrupts?
> > > > > > > > > > > > >
> > > > > > > > > > > > > Yup - you get a grumpy message from the driver, i=
t will refuse sampling
> > > > > > > > > > > > > events (the ones which weren't working anyway), a=
nd if you measure
> > > > > > > > > > > > > anything for long enough that a counter overflows=
 you'll get wonky
> > > > > > > > > > > > > results. But for counting hardware events over re=
latively short periods
> > > > > > > > > > > > > it'll still do the job.
> > > > > > > > > > > >
> > > > > > > > > > > > I tried to drop interrupts completely from the node=
 but 'perf top' is
> > > > > > > > > > > > still broken. Though now in different way: it compl=
ains "cycles: PMU
> > > > > > > > > > > > Hardware doesn't support sampling/overflow-interrup=
ts. Try 'perf
> > > > > > > > > > > > stat'"
> > > > > > > > > > >
> > > > > > > > > > > I have no idea if that's the culprit, but what is the=
 state of the
> > > > > > > > > > > 0x09010000 register?
> > > > > > > > > >
> > > > > > > > > > What register is that and how do I check it?
> > > > > > > > >
> > > > > > > > > It's in the CPUX Configuration block, and the bits are la=
belled as CPU
> > > > > > > > > Debug Reset.
> > > > > > > > >
> > > > > > > > > And if you have busybox, you can use devmem.
> > > > > > > >
> > > > > > > > CPUX configuration block is at 0x01700000 according to A64 =
user
> > > > > > > > manual, and particular register you're interested in is at =
0x01700080,
> > > > > > > > its value is 0x1110110F.
> > > > > > > >
> > > > > > > > Bits 16-19 are not defined in user manual and are not set.
> > > > > > >
> > > > > > > Sorry, I somehow thought this was for the H6...
> > > > > > >
> > > > > > > I don't have any idea then :/
> > > > > >
> > > > > > OK, so what should we do? 'perf top'/'perf record' work fine if=
 PMU
> > > > > > node is dropped, but they don't work if PMU node is present (ev=
en with
> > > > > > interrupts dropped). I'd prefer to have 'perf top' and 'perf re=
cord'
> > > > > > working instead of 'perf stat'
> > > > >
> > > > > Well, it doesn't work so we should just remove the node, and if
> > > > > someone wants it back, they should figure it out.
> > > >
> > > > Hey Maxime,
> > > >
> > > > So can you merge this patch?
> > >
> > > Added new Maxime's email to CC
> >
> > Queued as a fix for 5.4, thanks!
> > Maxime
> > _______________________________________________
> > linux-arm-kernel mailing list
> > linux-arm-kernel@lists.infradead.org
> > http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
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