linux.git/include/linux/cpufreq.h, branch v3.15 Clone of https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git cpufreq: create another field .flags in cpufreq_frequency_table 2014-04-07T12:43:50+00:00 Viresh Kumar viresh.kumar@linaro.org 2014-03-28T13:41:47+00:00 7f4b04614a273089ad65654f53771c033fadc65e Currently cpufreq frequency table has two fields: frequency and driver_data. driver_data is only for drivers' internal use and cpufreq core shouldn't use it at all. But with the introduction of BOOST frequencies, this assumption was broken and we started using it as a flag instead. There are two problems due to this: - It is against the description of this field, as driver's data is used by the core now. - if drivers fill it with -3 for any frequency, then those frequencies are never considered by cpufreq core as it is exactly same as value of CPUFREQ_BOOST_FREQ, i.e. ~2. The best way to get this fixed is by creating another field flags which will be used for such flags. This patch does that. Along with that various drivers need modifications due to the change of struct cpufreq_frequency_table. Reviewed-by: Gautham R Shenoy <ego@linux.vnet.ibm.com> Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> 
Currently cpufreq frequency table has two fields: frequency and driver_data.
driver_data is only for drivers' internal use and cpufreq core shouldn't use
it at all. But with the introduction of BOOST frequencies, this assumption
was broken and we started using it as a flag instead.

There are two problems due to this:
- It is against the description of this field, as driver's data is used by
  the core now.
- if drivers fill it with -3 for any frequency, then those frequencies are
  never considered by cpufreq core as it is exactly same as value of
  CPUFREQ_BOOST_FREQ, i.e. ~2.

The best way to get this fixed is by creating another field flags which
will be used for such flags. This patch does that. Along with that various
drivers need modifications due to the change of struct cpufreq_frequency_table.

Reviewed-by: Gautham R Shenoy <ego@linux.vnet.ibm.com>
Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
cpufreq: Make cpufreq_notify_transition & cpufreq_notify_post_transition static 2014-03-26T15:41:41+00:00 Viresh Kumar viresh.kumar@linaro.org 2014-03-24T08:05:46+00:00 236a98005274d8011136aee4aef52241588a9712 cpufreq_notify_transition() and cpufreq_notify_post_transition() shouldn't be called directly by cpufreq drivers anymore and so these should be marked static. Reviewed-by: Srivatsa S. Bhat <srivatsa.bhat@linux.vnet.ibm.com> Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> 
cpufreq_notify_transition() and cpufreq_notify_post_transition() shouldn't be
called directly by cpufreq drivers anymore and so these should be marked static.

Reviewed-by: Srivatsa S. Bhat <srivatsa.bhat@linux.vnet.ibm.com>
Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
cpufreq: Make sure frequency transitions are serialized 2014-03-26T15:41:40+00:00 Srivatsa S. Bhat srivatsa.bhat@linux.vnet.ibm.com 2014-03-24T08:05:44+00:00 12478cf0c55e5969f740bb38a24b1a0104ae18d8 Whenever we change the frequency of a CPU, we call the PRECHANGE and POSTCHANGE notifiers. They must be serialized, i.e. PRECHANGE and POSTCHANGE notifiers should strictly alternate, thereby preventing two different sets of PRECHANGE or POSTCHANGE notifiers from interleaving arbitrarily. The following examples illustrate why this is important: Scenario 1: ----------- A thread reading the value of cpuinfo_cur_freq, will call __cpufreq_cpu_get()->cpufreq_out_of_sync()->cpufreq_notify_transition() The ondemand governor can decide to change the frequency of the CPU at the same time and hence it can end up sending the notifications via ->target(). If the notifiers are not serialized, the following sequence can occur: - PRECHANGE Notification for freq A (from cpuinfo_cur_freq) - PRECHANGE Notification for freq B (from target()) - Freq changed by target() to B - POSTCHANGE Notification for freq B - POSTCHANGE Notification for freq A We can see from the above that the last POSTCHANGE Notification happens for freq A but the hardware is set to run at freq B. Where would we break then?: adjust_jiffies() in cpufreq.c & cpufreq_callback() in arch/arm/kernel/smp.c (which also adjusts the jiffies). All the loops_per_jiffy calculations will get messed up. Scenario 2: ----------- The governor calls __cpufreq_driver_target() to change the frequency. At the same time, if we change scaling_{min|max}_freq from sysfs, it will end up calling the governor's CPUFREQ_GOV_LIMITS notification, which will also call __cpufreq_driver_target(). And hence we end up issuing concurrent calls to ->target(). Typically, platforms have the following logic in their ->target() routines: (Eg: cpufreq-cpu0, omap, exynos, etc) A. If new freq is more than old: Increase voltage B. Change freq C. If new freq is less than old: decrease voltage Now, if the two concurrent calls to ->target() are X and Y, where X is trying to increase the freq and Y is trying to decrease it, we get the following race condition: X.A: voltage gets increased for larger freq Y.A: nothing happens Y.B: freq gets decreased Y.C: voltage gets decreased X.B: freq gets increased X.C: nothing happens Thus we can end up setting a freq which is not supported by the voltage we have set. That will probably make the clock to the CPU unstable and the system might not work properly anymore. This patch introduces a set of synchronization primitives to serialize frequency transitions, which are to be used as shown below: cpufreq_freq_transition_begin(); //Perform the frequency change cpufreq_freq_transition_end(); The _begin() call sends the PRECHANGE notification whereas the _end() call sends the POSTCHANGE notification. Also, all the necessary synchronization is handled within these calls. In particular, even drivers which set the ASYNC_NOTIFICATION flag can also use these APIs for performing frequency transitions (ie., you can call _begin() from one task, and call the corresponding _end() from a different task). The actual synchronization underneath is not that complicated: The key challenge is to allow drivers to begin the transition from one thread and end it in a completely different thread (this is to enable drivers that do asynchronous POSTCHANGE notification from bottom-halves, to also use the same interface). To achieve this, a 'transition_ongoing' flag, a 'transition_lock' spinlock and a wait-queue are added per-policy. The flag and the wait-queue are used in conjunction to create an "uninterrupted flow" from _begin() to _end(). The spinlock is used to ensure that only one such "flow" is in flight at any given time. Put together, this provides us all the necessary synchronization. Signed-off-by: Srivatsa S. Bhat <srivatsa.bhat@linux.vnet.ibm.com> Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> 
Whenever we change the frequency of a CPU, we call the PRECHANGE and POSTCHANGE
notifiers. They must be serialized, i.e. PRECHANGE and POSTCHANGE notifiers
should strictly alternate, thereby preventing two different sets of PRECHANGE or
POSTCHANGE notifiers from interleaving arbitrarily.

The following examples illustrate why this is important:

Scenario 1:
-----------
A thread reading the value of cpuinfo_cur_freq, will call
__cpufreq_cpu_get()->cpufreq_out_of_sync()->cpufreq_notify_transition()

The ondemand governor can decide to change the frequency of the CPU at the same
time and hence it can end up sending the notifications via ->target().

If the notifiers are not serialized, the following sequence can occur:
- PRECHANGE Notification for freq A (from cpuinfo_cur_freq)
- PRECHANGE Notification for freq B (from target())
- Freq changed by target() to B
- POSTCHANGE Notification for freq B
- POSTCHANGE Notification for freq A

We can see from the above that the last POSTCHANGE Notification happens for freq
A but the hardware is set to run at freq B.

Where would we break then?: adjust_jiffies() in cpufreq.c & cpufreq_callback()
in arch/arm/kernel/smp.c (which also adjusts the jiffies). All the
loops_per_jiffy calculations will get messed up.

Scenario 2:
-----------
The governor calls __cpufreq_driver_target() to change the frequency. At the
same time, if we change scaling_{min|max}_freq from sysfs, it will end up
calling the governor's CPUFREQ_GOV_LIMITS notification, which will also call
__cpufreq_driver_target(). And hence we end up issuing concurrent calls to
->target().

Typically, platforms have the following logic in their ->target() routines:
(Eg: cpufreq-cpu0, omap, exynos, etc)

A. If new freq is more than old: Increase voltage
B. Change freq
C. If new freq is less than old: decrease voltage

Now, if the two concurrent calls to ->target() are X and Y, where X is trying to
increase the freq and Y is trying to decrease it, we get the following race
condition:

X.A: voltage gets increased for larger freq
Y.A: nothing happens
Y.B: freq gets decreased
Y.C: voltage gets decreased
X.B: freq gets increased
X.C: nothing happens

Thus we can end up setting a freq which is not supported by the voltage we have
set. That will probably make the clock to the CPU unstable and the system might
not work properly anymore.

This patch introduces a set of synchronization primitives to serialize frequency
transitions, which are to be used as shown below:

cpufreq_freq_transition_begin();

//Perform the frequency change

cpufreq_freq_transition_end();

The _begin() call sends the PRECHANGE notification whereas the _end() call sends
the POSTCHANGE notification. Also, all the necessary synchronization is handled
within these calls. In particular, even drivers which set the ASYNC_NOTIFICATION
flag can also use these APIs for performing frequency transitions (ie., you can
call _begin() from one task, and call the corresponding _end() from a different
task).

The actual synchronization underneath is not that complicated:

The key challenge is to allow drivers to begin the transition from one thread
and end it in a completely different thread (this is to enable drivers that do
asynchronous POSTCHANGE notification from bottom-halves, to also use the same
interface).

To achieve this, a 'transition_ongoing' flag, a 'transition_lock' spinlock and a
wait-queue are added per-policy. The flag and the wait-queue are used in
conjunction to create an "uninterrupted flow" from _begin() to _end(). The
spinlock is used to ensure that only one such "flow" is in flight at any given
time. Put together, this provides us all the necessary synchronization.

Signed-off-by: Srivatsa S. Bhat <srivatsa.bhat@linux.vnet.ibm.com>
Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
cpufreq: Add stop CPU callback to cpufreq_driver interface 2014-03-20T02:50:12+00:00 Dirk Brandewie dirk.j.brandewie@intel.com 2014-03-19T15:45:53+00:00 367dc4aa932bfb33a3189064d33f7890a8ec1ca8 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 <dirk.j.brandewie@intel.com> [rjw: Minor modifications] Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> 
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 <dirk.j.brandewie@intel.com>
[rjw: Minor modifications]
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
cpufreq: remove unused notifier: CPUFREQ_{SUSPENDCHANGE|RESUMECHANGE} 2014-03-19T13:10:24+00:00 Viresh Kumar viresh.kumar@linaro.org 2014-03-19T05:54:58+00:00 0b443ead714f0cba797a7f2476dd756f22b5421e 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 <viresh.kumar@linaro.org> Reviewed-by: Srivatsa S. Bhat <srivatsa.bhat@linux.vnet.ibm.com> [rjw: Changelog] Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> 
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 <viresh.kumar@linaro.org>
Reviewed-by: Srivatsa S. Bhat <srivatsa.bhat@linux.vnet.ibm.com>
[rjw: Changelog]
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
cpufreq: Remove cpufreq_generic_exit() 2014-03-12T00:06:00+00:00 Viresh Kumar viresh.kumar@linaro.org 2014-03-10T09:23:34+00:00 979d86fac5e6dbf5c939e9a2a9fe294c9e05e42f cpufreq_generic_exit() is empty now and can be deleted. Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> 
cpufreq_generic_exit() is empty now and can be deleted.

Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
cpufreq: add 'freq_table' in struct cpufreq_policy 2014-03-12T00:06:00+00:00 Viresh Kumar viresh.kumar@linaro.org 2014-03-10T09:23:33+00:00 e0b3165ba521c6824b3e9f563f38a701dfa2d8e6 freq table is not per CPU but per policy, so it makes more sense to keep it within struct cpufreq_policy instead of a per-cpu variable. This patch does it. Over that, there is no need to set policy->freq_table to NULL in ->exit(), as policy structure is going to be freed soon. Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> 
freq table is not per CPU but per policy, so it makes more sense to
keep it within struct cpufreq_policy instead of a per-cpu variable.

This patch does it. Over that, there is no need to set policy->freq_table
to NULL in ->exit(), as policy structure is going to be freed soon.

Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
cpufreq: Implement cpufreq_generic_suspend() 2014-03-06T14:04:12+00:00 Viresh Kumar viresh.kumar@linaro.org 2014-03-04T03:00:27+00:00 e28867eab7c0a60cddf0cb59f9f6cbbd9561425d Multiple platforms need to set CPUs to a particular frequency before suspending the system, so provide a common infrastructure for them. Those platforms only need to point their ->suspend callback pointers to the generic routine. Tested-by: Stephen Warren <swarren@nvidia.com> Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org> [rjw: Changelog] Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> 
Multiple platforms need to set CPUs to a particular frequency before
suspending the system, so provide a common infrastructure for them.

Those platforms only need to point their ->suspend callback pointers
to the generic routine.

Tested-by: Stephen Warren <swarren@nvidia.com>
Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
[rjw: Changelog]
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
cpufreq: suspend governors on system suspend/hibernate 2014-03-06T14:04:12+00:00 Viresh Kumar viresh.kumar@linaro.org 2014-03-04T03:00:26+00:00 2f0aea9363609433b38ab13f0f86f38372668c68 This patch adds cpufreq suspend/resume calls to dpm_{suspend|resume}() for handling suspend/resume of cpufreq governors. Lan Tianyu (Intel) & Jinhyuk Choi (Broadcom) found an issue where the tunables configuration for clusters/sockets with non-boot CPUs was lost after system suspend/resume, as we were notifying governors with CPUFREQ_GOV_POLICY_EXIT on removal of the last CPU for that policy which caused the tunables memory to be freed. This is fixed by preventing any governor operations from being carried out between the device suspend and device resume stages of system suspend and resume, respectively. We could have added these callbacks at dpm_{suspend|resume}_noirq() level, but there is an additional problem that the majority of I/O devices is already suspended at that point and if cpufreq drivers want to change the frequency before suspending, then that not be possible on some platforms (which depend on peripherals like i2c, regulators, etc). Reported-and-tested-by: Lan Tianyu <tianyu.lan@intel.com> Reported-by: Jinhyuk Choi <jinchoi@broadcom.com> Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org> [rjw: Changelog] Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> 
This patch adds cpufreq suspend/resume calls to dpm_{suspend|resume}()
for handling suspend/resume of cpufreq governors.

Lan Tianyu (Intel) & Jinhyuk Choi (Broadcom) found an issue where the
tunables configuration for clusters/sockets with non-boot CPUs was
lost after system suspend/resume, as we were notifying governors with
CPUFREQ_GOV_POLICY_EXIT on removal of the last CPU for that policy
which caused the tunables memory to be freed.

This is fixed by preventing any governor operations from being
carried out between the device suspend and device resume stages of
system suspend and resume, respectively.

We could have added these callbacks at dpm_{suspend|resume}_noirq()
level, but there is an additional problem that the majority of I/O
devices is already suspended at that point and if cpufreq drivers
want to change the frequency before suspending, then that not be
possible on some platforms (which depend on peripherals like i2c,
regulators, etc).

Reported-and-tested-by: Lan Tianyu <tianyu.lan@intel.com>
Reported-by: Jinhyuk Choi <jinchoi@broadcom.com>
Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
[rjw: Changelog]
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
cpufreq: Add boost frequency support in core 2014-01-17T01:00:44+00:00 Lukasz Majewski l.majewski@samsung.com 2013-12-20T14:24:49+00:00 6f19efc0a1ca08bc61841b971d8b85ab505d95c8 This commit adds boost frequency support in cpufreq core (Hardware & Software). Some SoCs (like Exynos4 - e.g. 4x12) allow setting frequency above its normal operation limits. Such mode shall be only used for a short time. Overclocking (boost) support is essentially provided by platform dependent cpufreq driver. This commit unifies support for SW and HW (Intel) overclocking solutions in the core cpufreq driver. Previously the "boost" sysfs attribute was defined in the ACPI processor driver code. By default boost is disabled. One global attribute is available at: /sys/devices/system/cpu/cpufreq/boost. It only shows up when cpufreq driver supports overclocking. Under the hood frequencies dedicated for boosting are marked with a special flag (CPUFREQ_BOOST_FREQ) at driver's frequency table. It is the user's concern to enable/disable overclocking with a proper call to sysfs. The cpufreq_boost_trigger_state() function is defined non static on purpose. It is used later with thermal subsystem to provide automatic enable/disable of the BOOST feature. Signed-off-by: Lukasz Majewski <l.majewski@samsung.com> Signed-off-by: Myungjoo Ham <myungjoo.ham@samsung.com> Acked-by: Viresh Kumar <viresh.kumar@linaro.org> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> 
This commit adds boost frequency support in cpufreq core (Hardware &
Software). Some SoCs (like Exynos4 - e.g. 4x12) allow setting frequency
above its normal operation limits. Such mode shall be only used for a
short time.

Overclocking (boost) support is essentially provided by platform
dependent cpufreq driver.

This commit unifies support for SW and HW (Intel) overclocking solutions
in the core cpufreq driver. Previously the "boost" sysfs attribute was
defined in the ACPI processor driver code. By default boost is disabled.
One global attribute is available at: /sys/devices/system/cpu/cpufreq/boost.

It only shows up when cpufreq driver supports overclocking.
Under the hood frequencies dedicated for boosting are marked with a
special flag (CPUFREQ_BOOST_FREQ) at driver's frequency table.
It is the user's concern to enable/disable overclocking with a proper call
to sysfs.

The cpufreq_boost_trigger_state() function is defined non static on purpose.
It is used later with thermal subsystem to provide automatic enable/disable
of the BOOST feature.

Signed-off-by: Lukasz Majewski <l.majewski@samsung.com>
Signed-off-by: Myungjoo Ham <myungjoo.ham@samsung.com>
Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>