linux-kernel - Re: [PATCH v3 3/3] perf: xgene: Add support for SoC PMU version 3

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Message-ID: <20170622181749.GF25967@leverpostej>
Date:   Thu, 22 Jun 2017 19:17:49 +0100
From:   Mark Rutland <mark.rutland@....com>
To:     Hoan Tran <hotran@....com>
Cc:     Will Deacon <will.deacon@....com>,
        Jonathan Corbet <corbet@....net>,
        Tai Nguyen <ttnguyen@....com>,
        linux-arm-kernel@...ts.infradead.org,
        lkml <linux-kernel@...r.kernel.org>, linux-doc@...r.kernel.org,
        Loc Ho <lho@....com>
Subject: Re: [PATCH v3 3/3] perf: xgene: Add support for SoC PMU version 3

On Thu, Jun 22, 2017 at 11:13:08AM -0700, Hoan Tran wrote:
> On Thu, Jun 22, 2017 at 10:52 AM, Mark Rutland <mark.rutland@....com> wrote:
> > On Tue, Jun 06, 2017 at 11:02:26AM -0700, Hoan Tran wrote:
> > >  static inline void
> > > +xgene_pmu_write_counter64(struct xgene_pmu_dev *pmu_dev, int idx, u64 val)
> > > +{
> > > +     u32 cnt_lo, cnt_hi;
> > > +
> > > +     cnt_hi = upper_32_bits(val);
> > > +     cnt_lo = lower_32_bits(val);
> > > +
> > > +     /* v3 has 64-bit counter registers composed by 2 32-bit registers */
> > > +     xgene_pmu_write_counter32(pmu_dev, 2 * idx, cnt_lo);
> > > +     xgene_pmu_write_counter32(pmu_dev, 2 * idx + 1, cnt_hi);
> > > +}
> >
> > For this to be atomic, we need to disable the counters for the duration
> > of the IRQ handler, which we don't do today.
> >
> > Regardless, we should do that to ensure that groups are self-consistent.
> >
> > i.e. in xgene_pmu_isr() we should call ops->stop_counters() just after
> > taking the pmu lock, and we should call ops->start_counters() just
> > before releasing it.
> 
> Thanks for your comments. I'll fix them and send another version of
> patch set soon.

No need; I'm picking these up now, and I'll apply the fixups locally.

Thanks,
Mark.