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Merge back cpufreq material for v5.8.

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Rafael J. Wysocki 2020-05-02 22:00:56 +02:00
parent 8c539776ac 33aa46f252
commit 9795a0ddf8
2 changed files with 21 additions and 14 deletions
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32
Documentation/admin-guide/pm/intel_pstate.rst
View file

@ -62,9 +62,10 @@ on the capabilities of the processor.
Active Mode
-----------
This is the default operation mode of ``intel_pstate``. If it works in this
mode, the ``scaling_driver`` policy attribute in ``sysfs`` for all ``CPUFreq``
policies contains the string "intel_pstate".
This is the default operation mode of ``intel_pstate`` for processors with
hardware-managed P-states (HWP) support. If it works in this mode, the
``scaling_driver`` policy attribute in ``sysfs`` for all ``CPUFreq`` policies
contains the string "intel_pstate".
In this mode the driver bypasses the scaling governors layer of ``CPUFreq`` and
provides its own scaling algorithms for P-state selection. Those algorithms
@ -138,12 +139,13 @@ internal P-state selection logic to be less performance-focused.
Active Mode Without HWP
~~~~~~~~~~~~~~~~~~~~~~~
This is the default operation mode for processors that do not support the HWP
feature. It also is used by default with the ``intel_pstate=no_hwp`` argument
in the kernel command line. However, in this mode ``intel_pstate`` may refuse
to work with the given processor if it does not recognize it. [Note that
``intel_pstate`` will never refuse to work with any processor with the HWP
feature enabled.]
This operation mode is optional for processors that do not support the HWP
feature or when the ``intel_pstate=no_hwp`` argument is passed to the kernel in
the command line. The active mode is used in those cases if the
``intel_pstate=active`` argument is passed to the kernel in the command line.
In this mode ``intel_pstate`` may refuse to work with processors that are not
recognized by it. [Note that ``intel_pstate`` will never refuse to work with
any processor with the HWP feature enabled.]
In this mode ``intel_pstate`` registers utilization update callbacks with the
CPU scheduler in order to run a P-state selection algorithm, either
@ -188,10 +190,14 @@ is not set.
Passive Mode
------------
This mode is used if the ``intel_pstate=passive`` argument is passed to the
kernel in the command line (it implies the ``intel_pstate=no_hwp`` setting too).
Like in the active mode without HWP support, in this mode ``intel_pstate`` may
refuse to work with the given processor if it does not recognize it.
This is the default operation mode of ``intel_pstate`` for processors without
hardware-managed P-states (HWP) support. It is always used if the
``intel_pstate=passive`` argument is passed to the kernel in the command line
regardless of whether or not the given processor supports HWP. [Note that the
``intel_pstate=no_hwp`` setting implies ``intel_pstate=passive`` if it is used
without ``intel_pstate=active``.] Like in the active mode without HWP support,
in this mode ``intel_pstate`` may refuse to work with processors that are not
recognized by it.
If the driver works in this mode, the ``scaling_driver`` policy attribute in
``sysfs`` for all ``CPUFreq`` policies contains the string "intel_cpufreq".

3
drivers/cpufreq/intel_pstate.c
View file

@ -2771,6 +2771,8 @@ static int __init intel_pstate_init(void)
pr_info("Invalid MSRs\n");
return -ENODEV;
}
/* Without HWP start in the passive mode. */
default_driver = &intel_cpufreq;
hwp_cpu_matched:
/*
@ -2816,7 +2818,6 @@ static int __init intel_pstate_setup(char *str)
if (!strcmp(str, "disable")) {
no_load = 1;
} else if (!strcmp(str, "passive")) {
pr_info("Passive mode enabled\n");
default_driver = &intel_cpufreq;
no_hwp = 1;
}