On Tue, Jun 09, 2015 at 05:49:28PM +0530, Vineet Gupta wrote:
> From: Alexey Brodkin <abrodkin@xxxxxxxxxxxx>
-ENOCHANGELOG
> Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
> Cc: Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>
> Signed-off-by: Alexey Brodkin <abrodkin@xxxxxxxxxxxx>
> Signed-off-by: Vineet Gupta <vgupta@xxxxxxxxxxxx>
> ---
> struct arc_pmu {
> struct pmu pmu;
> + int has_interrupts;
we have pmu::flags & PERF_PMU_CAP_NO_INTERRUPT
> @@ -186,7 +189,8 @@ static int arc_pmu_event_init(struct perf_event *event)
> hwc->last_period = hwc->sample_period;
> local64_set(&hwc->period_left, hwc->sample_period);
> } else
> - return -ENOENT;
> + if (!arc_pmu->has_interrupts)
> + return -ENOENT;
Same as before, first determine if the event is yours, then return a
fatal error.
> @@ -307,6 +311,17 @@ static void arc_pmu_stop(struct perf_event *event, int flags)
> struct hw_perf_event *hwc = &event->hw;
> int idx = hwc->idx;
>
> + /* Disable interrupt for this counter */
> + if (is_sampling_event(event)) {
but but but, a sampling event needs the interrupt enabled?
> + /*
> + * Reset interrupt flag by writing of 1. This is required
> + * to make sure pending interrupt was not left.
> + */
Would not typically the interrupt latch be a property of the interrupt
controller, not the device generating it?
That is, how can the device programming affect pending interrupts?
> + write_aux_reg(ARC_REG_PCT_INT_ACT, 1 << idx);
> + write_aux_reg(ARC_REG_PCT_INT_CTRL,
> + read_aux_reg(ARC_REG_PCT_INT_CTRL) & ~(1 << idx));
> + }
> +
> + if (is_sampling_event(event)) {
> + /* Mimic full counter overflow as other arches do */
With this you mean the pretending we have 63bit of overflow counter?
> + write_aux_reg(ARC_REG_PCT_INT_CNTL, arc_pmu->max_period &
> + 0xffffffff);
Would not (u32)arc_pmu->max_period, be clearer?
> + write_aux_reg(ARC_REG_PCT_INT_CNTH,
> + (arc_pmu->max_period >> 32));
But should you not program: min(period, max_period) instead? If the
requested period is shorter than your max period you do not want to
program the max. Or are you missing a negative somewhere?
That is, program the max_period for !sampling events to deal with
overflow folding.
> +
> + /* Enable interrupt for this counter */
> + write_aux_reg(ARC_REG_PCT_INT_CTRL,
> + read_aux_reg(ARC_REG_PCT_INT_CTRL) | (1 << idx));
> + }
> +
> write_aux_reg(ARC_REG_PCT_CONFIG, 0);
> write_aux_reg(ARC_REG_PCT_COUNTL, 0);
> write_aux_reg(ARC_REG_PCT_COUNTH, 0);
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