0545e9dc6d
commit d1edce71135cc6d98c0a4b5729774542b676e769 Author: sophgo-forum-service <forum_service@sophgo.com> Date: Fri Mar 15 16:07:33 2024 +0800 [fix] recommend using ssh method to clone repo. [fix] fix sensor driver repo branch name.
34 lines
1.2 KiB
ReStructuredText
34 lines
1.2 KiB
ReStructuredText
.. SPDX-License-Identifier: GPL-2.0
|
|
|
|
===========================
|
|
Low Power Idle Table (LPIT)
|
|
===========================
|
|
|
|
To enumerate platform Low Power Idle states, Intel platforms are using
|
|
“Low Power Idle Table” (LPIT). More details about this table can be
|
|
downloaded from:
|
|
https://www.uefi.org/sites/default/files/resources/Intel_ACPI_Low_Power_S0_Idle.pdf
|
|
|
|
Residencies for each low power state can be read via FFH
|
|
(Function fixed hardware) or a memory mapped interface.
|
|
|
|
On platforms supporting S0ix sleep states, there can be two types of
|
|
residencies:
|
|
|
|
- CPU PKG C10 (Read via FFH interface)
|
|
- Platform Controller Hub (PCH) SLP_S0 (Read via memory mapped interface)
|
|
|
|
The following attributes are added dynamically to the cpuidle
|
|
sysfs attribute group::
|
|
|
|
/sys/devices/system/cpu/cpuidle/low_power_idle_cpu_residency_us
|
|
/sys/devices/system/cpu/cpuidle/low_power_idle_system_residency_us
|
|
|
|
The "low_power_idle_cpu_residency_us" attribute shows time spent
|
|
by the CPU package in PKG C10
|
|
|
|
The "low_power_idle_system_residency_us" attribute shows SLP_S0
|
|
residency, or system time spent with the SLP_S0# signal asserted.
|
|
This is the lowest possible system power state, achieved only when CPU is in
|
|
PKG C10 and all functional blocks in PCH are in a low power state.
|