diff options
| author | Anshuman Khandual <anshuman.khandual@arm.com> | 2023-10-13 05:43:54 +0300 |
|---|---|---|
| committer | Will Deacon <will@kernel.org> | 2023-10-19 18:35:04 +0300 |
| commit | 58f8fc57b1d314b5402c374a8c454ac7c870574c (patch) | |
| tree | 21092c343eae88eabea774239b6d50e159920cc0 /drivers/perf | |
| parent | 50b560783f7f71790bcf70e9e9855155fb0af8c1 (diff) | |
| download | linux-58f8fc57b1d314b5402c374a8c454ac7c870574c.tar.xz | |
drivers: perf: arm_pmuv3: Read PMMIR_EL1 unconditionally
Currently the PMUv3 driver only reads PMMIR_EL1 if the PMU implements
FEAT_PMUv3p4 and the STALL_SLOT event, but the check for STALL_SLOT event
isn't necessary and can be removed.
The check for STALL_SLOT event was introduced with the read of PMMIR_EL1 in
commit f5be3a61fdb5dd11 ("arm64: perf: Add support caps under sysfs")
When this logic was written, the ARM ARM said:
| If STALL_SLOT is not implemented, it is IMPLEMENTATION DEFINED whether
| the PMMIR System registers are implemented.
... and thus the driver had to check for STALL_SLOT event to verify that
PMMIR_EL1 was implemented and accesses to PMMIR_EL1 would not be UNDEFINED.
Subsequently, the architecture was retrospectively tightened to require
that any FEAT_PMUv3p4 implementation implements PMMIR_EL1. Since the G.b
release of the ARM ARM, the wording regarding STALL_SLOT event has been
removed, and the description of PMMIR_EL1 says:
| This register is present only when FEAT_PMUv3p4 is implemented.
Drop the unnecessary check for STALL_SLOT event when reading PMMIR_EL1.
Cc: Will Deacon <will@kernel.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: linux-arm-kernel@lists.infradead.org
Cc: linux-kernel@vger.kernel.org
Reviewed-by: James Clark <james.clark@arm.com>
Signed-off-by: Anshuman Khandual <anshuman.khandual@arm.com>
Link: https://lore.kernel.org/r/20231013024354.1289070-1-anshuman.khandual@arm.com
Signed-off-by: Will Deacon <will@kernel.org>
Diffstat (limited to 'drivers/perf')
| -rw-r--r-- | drivers/perf/arm_pmuv3.c | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/drivers/perf/arm_pmuv3.c b/drivers/perf/arm_pmuv3.c index 8fcaa26f0f8a..4ee0afe00527 100644 --- a/drivers/perf/arm_pmuv3.c +++ b/drivers/perf/arm_pmuv3.c @@ -1126,7 +1126,7 @@ static void __armv8pmu_probe_pmu(void *info) pmceid, ARMV8_PMUV3_MAX_COMMON_EVENTS); /* store PMMIR register for sysfs */ - if (is_pmuv3p4(pmuver) && (pmceid_raw[1] & BIT(31))) + if (is_pmuv3p4(pmuver)) cpu_pmu->reg_pmmir = read_pmmir(); else cpu_pmu->reg_pmmir = 0; |