Commit e4e9b7b3 authored by Mario Limonciello's avatar Mario Limonciello Committed by Mario Limonciello (AMD)
Browse files

cpufreq/amd-pstate: Drop Kconfig option for dynamic EPP 



There are some performance issues being identified by dynamic EPP
and we don't want to have distributions turning it on by default
exposing them to users at this time.

Drop the kconfig option, and require an explicit opt in from kernel
command line or runtime sysfs option to turn it on.

Reported-by: default avatarViktor Jägersküpper <viktor_jaegerskuepper@freenet.de>
Closes: https://lore.kernel.org/linux-pm/14a87c99-785c-4b16-bfce-35ecbf053448@freenet.de/


Reported-by: default avatarStuart Meckle <stuartmeckle@gmail.com>
Closes: https://bugzilla.kernel.org/show_bug.cgi?id=221473


Signed-off-by: default avatarMario Limonciello <mario.limonciello@amd.com>
Reviewed-by: default avatarK Prateek Nayak <kprateek.nayak@amd.com>
Link: https://lore.kernel.org/r/20260512221947.1652988-1-mario.limonciello@amd.com


(fix sysfs file path)
Signed-off-by: default avatarMario Limonciello (AMD) <superm1@kernel.org>
parent f9f16835

Documentation/admin-guide/pm/amd-pstate.rst

+5 −6
Original line number Diff line number Diff line
@@ -358,9 +358,9 @@ Dynamic energy performance profile 
The amd-pstate driver supports dynamically selecting the energy performance

profile based on whether the machine is running on AC or DC power.



Whether this behavior is enabled by default depends on the kernel

config option `CONFIG_X86_AMD_PSTATE_DYNAMIC_EPP`. This behavior can also be overridden

at runtime by the sysfs file ``/sys/devices/system/cpu/cpufreq/policyX/dynamic_epp``.

Whether this behavior is enabled by default depends on the kernel command line option

``amd_dynamic_epp`` is set. This behavior can also be overridden

at runtime by the sysfs file ``/sys/devices/system/cpu/amd_pstate/dynamic_epp``.



When set to enabled, the driver will select a different energy performance

profile when the machine is running on battery or AC power. The driver will
@@ -485,9 +485,8 @@ kernel parameter ``amd_prefcore=disable``. 
``amd_dynamic_epp``



When AMD pstate is in auto mode, dynamic EPP will control whether the kernel

autonomously changes the EPP mode. The default is configured by

``CONFIG_X86_AMD_PSTATE_DYNAMIC_EPP`` but can be explicitly enabled with

``amd_dynamic_epp=enable`` or disabled with ``amd_dynamic_epp=disable``.

autonomously changes the EPP mode. The default is disabled. It can be enabled

with the kernel parameter ``amd_dynamic_epp=enable``.



User Space Interface in ``sysfs`` - General

===========================================

drivers/cpufreq/Kconfig.x86

+0 −12
Original line number Diff line number Diff line
@@ -70,18 +70,6 @@ config X86_AMD_PSTATE_DEFAULT_MODE 
	  For details, take a look at:

	  <file:Documentation/admin-guide/pm/amd-pstate.rst>.



config X86_AMD_PSTATE_DYNAMIC_EPP

	bool "AMD Processor P-State dynamic EPP support"

	depends on X86_AMD_PSTATE

	default n

	help

	  Allow the kernel to dynamically change the energy performance

	  value from events like ACPI platform profile and AC adapter plug

	  events.



	  This feature can also be changed at runtime, this configuration

	  option only sets the kernel default value behavior.



config X86_AMD_PSTATE_UT

	tristate "selftest for AMD Processor P-State driver"

	depends on X86 && ACPI_PROCESSOR

drivers/cpufreq/amd-pstate.c

+0 −4
Original line number Diff line number Diff line
@@ -87,11 +87,7 @@ static struct cpufreq_driver amd_pstate_driver; 
static struct cpufreq_driver amd_pstate_epp_driver;

static int cppc_state = AMD_PSTATE_UNDEFINED;

static bool amd_pstate_prefcore = true;

#ifdef CONFIG_X86_AMD_PSTATE_DYNAMIC_EPP

static bool dynamic_epp = CONFIG_X86_AMD_PSTATE_DYNAMIC_EPP;

#else

static bool dynamic_epp;

#endif

static struct quirk_entry *quirks;



/*