Re: [PATCH v7 2/4] perf/smmuv3: Add arm64 smmuv3 pmu driver

[Robin Murphy]

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.mur...@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.mur...@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