[PATCH 0/2] Add ACPI C4 support

Mario Limonciello (AMD)
2025-09-15T20:43:23Z

Some AMD systems have introduced support for ACPI C4. Systems that
support ACPI C4 will enter CPU OFF at ACPI C3 and VDD OFF at ACPI C4.

VDD OFF is a requirement for s0i3, and thus if C4 isn't supported then
a system can't enter s0i3.

Add support for ACPI C4 to the processor idle driver, following similar
semantics of ACPI C3.

Mario Limonciello (AMD) (2):
x86/acpi/cstate: Remove open coded check for cpu_feature_enabled()
ACPI: processor: Add support for ACPI C4 state

arch/x86/kernel/acpi/cstate.c | 2 +-
drivers/acpi/processor_idle.c | 10 +++++++---
include/acpi/actypes.h | 5 +++--
3 files changed, 11 insertions(+), 6 deletions(-)

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2.43.0