linux-toradex.git/Documentation/cpu-freq, branch v4.1.10

intel_pstate: Add num_pstates to sysfs

2015-01-30T00:52:17+00:00

Add a sysfs interface to display the total number of supported
pstates.  This value is independent of whether turbo has been
enabled or disabled.

Signed-off-by: Kristen Carlson Accardi 
Signed-off-by: Rafael J. Wysocki

intel_pstate: expose turbo range to sysfs

2015-01-30T00:52:17+00:00

This patch adds "turbo_pct" to the intel_pstate sysfs interface.
turbo_pct will display the percentage of the total supported
pstates that are in the turbo range.  This value is independent
of whether turbo has been disabled or not.

Signed-off-by: Kristen Carlson Accardi 
Signed-off-by: Rafael J. Wysocki

intel_pstate: Add support for HWP

2014-11-11T23:04:38+00:00

Add support of Hardware Managed Performance States (HWP) described in Volume 3
section 14.4 of the SDM.

With HWP enbaled intel_pstate will no longer be responsible for selecting P
states for the processor. intel_pstate will continue to register to
the cpufreq core as the scaling driver for CPUs implementing
HWP. In HWP mode intel_pstate provides three functions reporting
frequency to the cpufreq core, support for the set_policy() interface
from the core and maintaining the intel_pstate sysfs interface in
/sys/devices/system/cpu/intel_pstate.  User preferences expressed via
the set_policy() interface or the sysfs interface are forwared to the
CPU via the HWP MSR interface.

Signed-off-by: Dirk Brandewie 
Signed-off-by: Rafael J. Wysocki

intel_pstate: Update documentation of {max,min}_perf_pct sysfs files

2014-07-06T23:22:19+00:00

Update documentation to make the interpretation of the values clearer

Link: https://bugzilla.kernel.org/show_bug.cgi?id=64251
Cc: 3.13+   # 3.13+
Signed-off-by: Dirk Brandewie 
Signed-off-by: Rafael J. Wysocki

cpufreq: add support for intermediate (stable) frequencies

2014-06-05T21:32:29+00:00

Douglas Anderson, recently pointed out an interesting problem due to which
udelay() was expiring earlier than it should.

While transitioning between frequencies few platforms may temporarily switch to
a stable frequency, waiting for the main PLL to stabilize.

For example: When we transition between very low frequencies on exynos, like
between 200MHz and 300MHz, we may temporarily switch to a PLL running at 800MHz.
No CPUFREQ notification is sent for that. That means there's a period of time
when we're running at 800MHz but loops_per_jiffy is calibrated at between 200MHz
and 300MHz. And so udelay behaves badly.

To get this fixed in a generic way, introduce another set of callbacks
get_intermediate() and target_intermediate(), only for drivers with
target_index() and CPUFREQ_ASYNC_NOTIFICATION unset.

get_intermediate() should return a stable intermediate frequency platform wants
to switch to, and target_intermediate() should set CPU to that frequency,
before jumping to the frequency corresponding to 'index'. Core will take care of
sending notifications and driver doesn't have to handle them in
target_intermediate() or target_index().

NOTE: ->target_index() should restore to policy->restore_freq in case of
failures as core would send notifications for that.

Tested-by: Stephen Warren 
Signed-off-by: Viresh Kumar 
Reviewed-by: Doug Anderson 
Signed-off-by: Rafael J. Wysocki

PM / OPP: Move cpufreq specific OPP functions out of generic OPP library

2014-05-06T22:39:03+00:00

CPUFreq specific helper functions for OPP (Operating Performance Points)
now use generic OPP functions that allow CPUFreq to be be moved back
into CPUFreq framework. This allows for independent modifications
or future enhancements as needed isolated to just CPUFreq framework
alone.

Here, we just move relevant code and documentation to make this part of
CPUFreq infrastructure.

Cc: Kevin Hilman 
Signed-off-by: Nishanth Menon 
Acked-by: Viresh Kumar 
Signed-off-by: Rafael J. Wysocki

cpufreq: Make linux-pm@vger.kernel.org official mailing list

2014-04-30T23:15:32+00:00

There has been confusion all the time about which mailing list to follow
for cpufreq activities, linux-pm@vger.kernel.org or cpufreq@vger.kernel.org.

Since patches sent to cpufreq@vger.kernel.org don't go to Patchwork
which is a maintenance workflow problem, make linux-pm@vger.kernel.org
the official mailing list for cpufreq stuff and remove all references
of cpufreq@vger.kernel.org from kernel source.

Later, we can request that the list be dropped entirely.

Signed-off-by: Viresh Kumar 
[rjw: Changelog]
Signed-off-by: Rafael J. Wysocki

cpufreq: Introduce macros for cpufreq_frequency_table iteration

2014-04-29T22:05:31+00:00

Many cpufreq drivers need to iterate over the cpufreq_frequency_table
for various tasks.

This patch introduces two macros which can be used for iteration over
cpufreq_frequency_table keeping a common coding style across drivers:

- cpufreq_for_each_entry: iterate over each entry of the table
- cpufreq_for_each_valid_entry: iterate over each entry that contains
a valid frequency.

It should have no functional changes.

Signed-off-by: Stratos Karafotis 
Acked-by: Lad, Prabhakar 
Acked-by: Viresh Kumar 
Signed-off-by: Rafael J. Wysocki

cpufreq: Add stop CPU callback to cpufreq_driver interface

2014-03-20T02:50:12+00:00

This callback allows the driver to do clean up before the CPU is
completely down and its state cannot be modified.  This is used
by the intel_pstate driver to reduce the requested P state prior to
the core going away.  This is required because the requested P state
of the offline core is used to select the package P state. This
effectively sets the floor package P state to the requested P state on
the offline core.

Signed-off-by: Dirk Brandewie 
[rjw: Minor modifications]
Signed-off-by: Rafael J. Wysocki

cpufreq: remove unused notifier: CPUFREQ_{SUSPENDCHANGE|RESUMECHANGE}

2014-03-19T13:10:24+00:00

Two cpufreq notifiers CPUFREQ_RESUMECHANGE and CPUFREQ_SUSPENDCHANGE have
not been used for some time, so remove them to clean up code a bit.

Signed-off-by: Viresh Kumar 
Reviewed-by: Srivatsa S. Bhat 
[rjw: Changelog]
Signed-off-by: Rafael J. Wysocki