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

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Message-ID: <CAFHUOYz_WpYa9BhCnQ+ze5-mbM4pWSn84j_EyH0E16ZbAs43tQ@mail.gmail.com>
Date:   Thu, 22 Jun 2017 11:13:08 -0700
From:   Hoan Tran <hotran@....com>
To:     Mark Rutland <mark.rutland@....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

Hi Mark,

On Thu, Jun 22, 2017 at 10:52 AM, Mark Rutland <mark.rutland@....com> wrote:
>
> Hi Hoan,
>
> This largely looks good; I have one minor comment.
>
> 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.

Thanks
Hoan


>
>
> With that:
>
> Acked-by: Mark Rutland <mark.rutland@....com>
>
> Thanks,
> Mark.