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perf/arm-cmn: Fix DTC reset

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[ Upstream commit 71746c995cac92fcf6a65661b51211cf2009d7f0 ]

It turns out that my naive DTC reset logic fails to work as intended,
since, after checking with the hardware designers, the PMU actually
needs to be fully enabled in order to correctly clear any pending
overflows. Therefore, invert the sequence to start with turning on both
enables so that we can reliably get the DTCs into a known state, then
moving to our normal counters-stopped state from there. Since all the
DTM counters have already been unpaired during the initial discovery
pass, we just need to additionally reset the cycle counters to ensure
that no other unexpected overflows occur during this period.

Fixes: 0ba64770a2 ("perf: Add Arm CMN-600 PMU driver")
Reported-by: Geoff Blake <blakgeof@amazon.com>
Signed-off-by: Robin Murphy <robin.murphy@arm.com>
Link: https://lore.kernel.org/r/0ea4559261ea394f827c9aee5168c77a60aaee03.1684946389.git.robin.murphy@arm.com
Signed-off-by: Will Deacon <will@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
This commit is contained in:
Robin Murphy 2023-05-24 17:44:32 +01:00 committed by Greg Kroah-Hartman
parent 6368a71dca
commit 3e03681f07
1 changed files with 4 additions and 3 deletions
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7
drivers/perf/arm-cmn.c
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@ -1898,9 +1898,10 @@ static int arm_cmn_init_dtc(struct arm_cmn *cmn, struct arm_cmn_node *dn, int id
if (dtc->irq < 0)
return dtc->irq;
writel_relaxed(0, dtc->base + CMN_DT_PMCR);
writel_relaxed(CMN_DT_DTC_CTL_DT_EN, dtc->base + CMN_DT_DTC_CTL);
writel_relaxed(CMN_DT_PMCR_PMU_EN | CMN_DT_PMCR_OVFL_INTR_EN, dtc->base + CMN_DT_PMCR);
writeq_relaxed(0, dtc->base + CMN_DT_PMCCNTR);
writel_relaxed(0x1ff, dtc->base + CMN_DT_PMOVSR_CLR);
writel_relaxed(CMN_DT_PMCR_OVFL_INTR_EN, dtc->base + CMN_DT_PMCR);
return 0;
}
@ -1960,7 +1961,7 @@ static int arm_cmn_init_dtcs(struct arm_cmn *cmn)
dn->type = CMN_TYPE_CCLA;
}
writel_relaxed(CMN_DT_DTC_CTL_DT_EN, cmn->dtc[0].base + CMN_DT_DTC_CTL);
arm_cmn_set_state(cmn, CMN_STATE_DISABLED);
return 0;
}