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 <[email protected]>
Cc: Mark Rutland <[email protected]>
Cc: [email protected]
Cc: [email protected]
Reviewed-by: James Clark <[email protected]>
Signed-off-by: Anshuman Khandual <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Will Deacon <[email protected]>

0 files changed, 0 insertions, 0 deletions