tree 5557edd70233ffa3ee3412be5ce7830861f542f5
parent 3a5be9b8f43346a24f31c0017cb2566a6b2c72c5
author Rafael J. Wysocki <rafael.j.wysocki@intel.com> 1580727438 +0100
committer Rafael J. Wysocki <rafael.j.wysocki@intel.com> 1580727438 +0100

intel_idle: Introduce 'states_off' module parameter

In certain system configurations it may not be desirable to use some
C-states assumed to be available by intel_idle and the driver needs
to be prevented from using them even before the cpuidle sysfs
interface becomes accessible to user space.  Currently, the only way
to achieve that is by setting the 'max_cstate' module parameter to a
value lower than the index of the shallowest of the C-states in
question, but that may be overly intrusive, because it effectively
makes all of the idle states deeper than the 'max_cstate' one go
away (and the C-state to avoid may be in the middle of the range
normally regarded as available).

To allow that limitation to be overcome, introduce a new module
parameter called 'states_off' to represent a list of idle states to
be disabled by default in the form of a bitmask and update the
documentation to cover it.

Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>