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Commit ae2df912 authored by Jeremy Linton's avatar Jeremy Linton Committed by Rafael J. Wysocki
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ACPI: CPPC: Disable FIE if registers in PCC regions



PCC regions utilize a mailbox to set/retrieve register values used by
the CPPC code. This is fine as long as the operations are
infrequent. With the FIE code enabled though the overhead can range
from 2-11% of system CPU overhead (ex: as measured by top) on Arm
based machines.

So, before enabling FIE assure none of the registers used by
cppc_get_perf_ctrs() are in the PCC region. Finally, add a module
parameter which can override the PCC region detection at boot or
module reload.

Signed-off-by: default avatarJeremy Linton <jeremy.linton@arm.com>
Acked-by: default avatarViresh Kumar <viresh.kumar@linaro.org>
Reviewed-by: default avatarIonela Voinescu <ionela.voinescu@arm.com>
Signed-off-by: default avatarRafael J. Wysocki <rafael.j.wysocki@intel.com>
parent a2a9d185
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