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SubjectRe: [PATCH v7 2/4] perf/smmuv3: Add arm64 smmuv3 pmu driver
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Hi Shameer,

On 26/03/2019 15:17, Shameer Kolothum wrote:
[...]
> +static int smmu_pmu_apply_event_filter(struct smmu_pmu *smmu_pmu,
> + struct perf_event *event, int idx)
> +{
> + u32 span, sid;
> + unsigned int num_ctrs = smmu_pmu->num_counters;
> + bool filter_en = !!get_filter_enable(event);
> +
> + span = filter_en ? get_filter_span(event) :
> + SMMU_PMCG_DEFAULT_FILTER_SPAN;
> + sid = filter_en ? get_filter_stream_id(event) :
> + SMMU_PMCG_DEFAULT_FILTER_SID;
> +
> + /* Support individual filter settings */
> + if (!smmu_pmu->global_filter) {
> + smmu_pmu_set_event_filter(event, idx, span, sid);
> + return 0;
> + }
> +
> + /* Requested settings same as current global settings*/
> + if (span == smmu_pmu->global_filter_span &&
> + sid == smmu_pmu->global_filter_sid)
> + return 0;
> +
> + if (!bitmap_empty(smmu_pmu->used_counters, num_ctrs))
> + return -EAGAIN;
> +
> + if (idx == 0) {
> + smmu_pmu_set_event_filter(event, idx, span, sid);
> + smmu_pmu->global_filter_span = span;
> + smmu_pmu->global_filter_sid = sid;
> + return 0;
> + }

When I suggested dropping the check of idx, I did mean removing it
entirely, not just moving it further down ;)

Nothing to worry about though, I'll just leave this here for Will to
consider applying on top or squashing.

Thanks,
Robin.

----->8-----
From: Robin Murphy <robin.murphy@arm.com>
Subject: [PATCH] perf/smmuv3: Relax global filter constraint a little

Although the current behaviour of smmu_pmu_get_event_idx() effectively
ensures that the first-allocated counter will be counter 0, there's no
need to strictly enforce that in smmu_pmu_apply_event_filter(). All that
matters is that we only ever touch the global filter settings in
SMMU_PMCG_SMR0 and SMMU_PMCG_EVTYPER0 while no counters are active.

Signed-off-by: Robin Murphy <robin.murphy@arm.com>
---
drivers/perf/arm_smmuv3_pmu.c | 11 ++++-------
1 file changed, 4 insertions(+), 7 deletions(-)

diff --git a/drivers/perf/arm_smmuv3_pmu.c b/drivers/perf/arm_smmuv3_pmu.c
index 6b3c0ed7ad71..23045ead6de1 100644
--- a/drivers/perf/arm_smmuv3_pmu.c
+++ b/drivers/perf/arm_smmuv3_pmu.c
@@ -286,14 +286,11 @@ static int smmu_pmu_apply_event_filter(struct
smmu_pmu *smmu_pmu,
if (!bitmap_empty(smmu_pmu->used_counters, num_ctrs))
return -EAGAIN;

- if (idx == 0) {
- smmu_pmu_set_event_filter(event, idx, span, sid);
- smmu_pmu->global_filter_span = span;
- smmu_pmu->global_filter_sid = sid;
- return 0;
- }
+ smmu_pmu_set_event_filter(event, 0, span, sid);
+ smmu_pmu->global_filter_span = span;
+ smmu_pmu->global_filter_sid = sid;

- return -EAGAIN;
+ return 0;
}

static int smmu_pmu_get_event_idx(struct smmu_pmu *smmu_pmu,
--
2.20.1.dirty
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