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Date: Thu, 22 Jun 2017 11:28:27 -0700 From: Hoan Tran <hotran@....com> To: Mark Rutland <mark.rutland@....com> Cc: linux-doc@...r.kernel.org, Jonathan Corbet <corbet@....net>, Will Deacon <will.deacon@....com>, lkml <linux-kernel@...r.kernel.org>, Loc Ho <lho@....com>, linux-arm-kernel@...ts.infradead.org, Tai Nguyen <ttnguyen@....com> Subject: Re: [PATCH v3 3/3] perf: xgene: Add support for SoC PMU version 3 Hi Mark, On Thu, Jun 22, 2017 at 11:18 AM, Mark Rutland <mark.rutland@....com> wrote: > On Thu, Jun 22, 2017 at 06:52:56PM +0100, Mark Rutland 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. >> >> With that: >> >> Acked-by: Mark Rutland <mark.rutland@....com> > > Actually, that should be in _xgene_pmu_isr, given we have to do it for each > pmu_dev. > > I'll apply the diff below; this also avoids a race on V1 where an > overflow could be lost (as we clear the whole OVSR rather than only the > set bits). Yes, I'm good about that. Thanks Regards Hoan > > Thanks, > Mark. > > diff --git a/drivers/perf/xgene_pmu.c b/drivers/perf/xgene_pmu.c > index 84c32e0..a9659cb 100644 > --- a/drivers/perf/xgene_pmu.c > +++ b/drivers/perf/xgene_pmu.c > @@ -1217,13 +1217,15 @@ static void _xgene_pmu_isr(int irq, struct xgene_pmu_dev *pmu_dev) > u32 pmovsr; > int idx; > > + xgene_pmu->ops->stop_counters(pmu_dev); > + > if (xgene_pmu->version == PCP_PMU_V3) > pmovsr = readl(csr + PMU_PMOVSSET) & PMU_OVERFLOW_MASK; > else > pmovsr = readl(csr + PMU_PMOVSR) & PMU_OVERFLOW_MASK; > > if (!pmovsr) > - return; > + goto out; > > /* Clear interrupt flag */ > if (xgene_pmu->version == PCP_PMU_V1) > @@ -1243,6 +1245,9 @@ static void _xgene_pmu_isr(int irq, struct xgene_pmu_dev *pmu_dev) > xgene_perf_event_update(event); > xgene_perf_event_set_period(event); > } > + > +out: > + xgene_pmu->ops->start_counters(pmu_dev); > } > > static irqreturn_t xgene_pmu_isr(int irq, void *dev_id) >
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