tree c90b08996ecc564dd13ab08cb3e92616cc69150b
parent 167e61438da0664cab87c825a6c0cb83510d578e
author Mark Rutland <mark.rutland@arm.com> 1518628917 +0000
committer Will Deacon <will.deacon@arm.com> 1519126494 +0000

arm64: perf: correct PMUVer probing

The ID_AA64DFR0_EL1.PMUVer field doesn't follow the usual ID registers
scheme. While value 0xf indicates a non-architected PMU is implemented,
values 0x1 to 0xe indicate an increasingly featureful architected PMU,
as if the field were unsigned.

For more details, see ARM DDI 0487C.a, D10.1.4, "Alternative ID scheme
used for the Performance Monitors Extension version".

Currently, we treat the field as signed, and erroneously bail out for
values 0x8 to 0xe. Let's correct that.

Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Reviewed-by: Robin Murphy <robin.murphy@arm.com>
Cc: Will Deacon <will.deacon@arm.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>