[PATCH 0/3] intel_idle: Drop C-states redundant when PC6 is disabled

[Artem Bityutskiy <dedekind1@gmail.com>]

From: Artem Bityutskiy <artem.bityutskiy@linux.intel.com>

This patch series drops redundant requestable C-states when PC6 is disabled in
BIOS. For example, Granite Rapids Xeon has two C6 flavors: C6 and C6P. C6
allows only core C6 (CC6), while C6P allows both CC6 and package C6 (PC6).
When PC6 is disabled, C6P becomes identical to C6 and is therefore redundant.
Refer to patch 3 for the full rationale and details.

Patches 1 and 2 prepare the code for patch 3. They introduce no functional
changes, only restructure it to improve readability and maintainability.

For more information about Granite Rapids C6 vs C6P, refer to this article:
https://github.com/intel/pepc/blob/main/docs/misc-c6p-c6sp.md

Thanks, Artem.

Artem Bityutskiy (3):
  intel_idle: Add constants for MSR_PKG_CST_CONFIG_CONTROL
  intel_idle: Introduce a helper for checking PC6
  intel_idle: Drop C-states redundant when PC6 is disabled

 drivers/idle/intel_idle.c | 104 +++++++++++++++++++++++++++++---------
 1 file changed, 81 insertions(+), 23 deletions(-)

-- 
2.53.0