Hi Mark,
On Thu, Jun 22, 2017 at 11:18 AM, Mark Rutland <mark.rutland@xxxxxxx> 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@xxxxxxx>
>
> 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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