linux-kernel - Re: [PATCH] arm: bcm2835: Add the PMU to the devicetree.

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Date:   Thu, 17 May 2018 20:07:59 +0200
From:   Peter Zijlstra <peterz@...radead.org>
To:     Stefan Wahren <stefan.wahren@...e.com>
Cc:     Ingo Molnar <mingo@...hat.com>,
        Arnaldo Carvalho de Melo <acme@...nel.org>,
        Florian Fainelli <f.fainelli@...il.com>,
        linux-rpi-kernel@...ts.infradead.org,
        bcm-kernel-feedback-list@...adcom.com,
        Vince Weaver <vincent.weaver@...ne.edu>,
        linux-kernel@...r.kernel.org, Eric Anholt <eric@...olt.net>,
        linux-arm-kernel@...ts.infradead.org,
        Mark Rutland <mark.rutland@....com>
Subject: Re: [PATCH] arm: bcm2835: Add the PMU to the devicetree.

On Thu, May 17, 2018 at 06:55:26PM +0200, Stefan Wahren wrote:
> > Vince Weaver <vincent.weaver@...ne.edu> hat am 17. Mai 2018 um 18:34 geschrieben:
> > On Thu, 17 May 2018, Stefan Wahren wrote:
> > > > Eric Anholt <eric@...olt.net> hat am 17. Mai 2018 um 15:17 geschrieben:

> > > > The a53 and a7 counters seem to match up, so we advertise a7 so that
> > > > arm32 can probe.
> > 
> > so how closely did you look at the a53/a7 differences?  I see some major 
> > differences, especially with the CPU_CYCLES event (0xff vs 0x11).
> > 
> > The proper fix here might be to add a cortex-a53 PMU entry to the armv7 
> > code rather than trying to treat it as a cortex-a7.
> 
> we like to use the PMU of BCM2837 SoC (4x A53 cores) under arm32 and arm64.
> 
> What is the right way (tm) to the define the DT compatibles?
> Does the arm32 PMU driver need patching for proper A53 support?

I'm completely clueless on all of this; Mark might have ideas.