cpufreq: vexpress: Convert to platform remove callback returning void

The .remove() callback for a platform driver returns an int which makes
many driver authors wrongly assume it's possible to do e

cpufreq: vexpress: Convert to platform remove callback returning void

The .remove() callback for a platform driver returns an int which makes
many driver authors wrongly assume it's possible to do error handling by
returning an error code. However the value returned is (mostly) ignored
and this typically results in resource leaks. To improve here there is a
quest to make the remove callback return void. In the first step of this
quest all drivers are converted to .remove_new() which already returns
void.

Trivially convert this driver from always returning zero in the remove
callback to the void returning variant.

Cc: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Signed-off-by: Yangtao Li <frank.li@vivo.com>
Reviewed-by: Sudeep Holla <sudeep.holla@arm.com>
Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>

show more ...

cpufreq: Explicitly include correct DT includes

The DT of_device.h and of_platform.h date back to the separate
of_platform_bus_type before it as merged into the regular platform bus.
As part of that

cpufreq: Explicitly include correct DT includes

The DT of_device.h and of_platform.h date back to the separate
of_platform_bus_type before it as merged into the regular platform bus.
As part of that merge prepping Arm DT support 13 years ago, they
"temporarily" include each other. They also include platform_device.h
and of.h. As a result, there's a pretty much random mix of those include
files used throughout the tree. In order to detangle these headers and
replace the implicit includes with struct declarations, users need to
explicitly include the correct includes.

Signed-off-by: Rob Herring <robh@kernel.org>
Acked-by: Rafael J. Wysocki <rafael@kernel.org>
Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>

show more ...

cpufreq: vexpress: Drop unused variable

arm:allmodconfig fails to build with the following error.

drivers/cpufreq/vexpress-spc-cpufreq.c:454:13: error:
unused variable 'cur_cluster'

Remove th

cpufreq: vexpress: Drop unused variable

arm:allmodconfig fails to build with the following error.

drivers/cpufreq/vexpress-spc-cpufreq.c:454:13: error:
unused variable 'cur_cluster'

Remove the unused variable.

Fixes: bb8c26d9387f ("cpufreq: vexpress: Set CPUFREQ_IS_COOLING_DEV flag")
Cc: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Reviewed-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>

show more ...

cpufreq: vexpress: Drop unused variable

arm:allmodconfig fails to build with the following error.

drivers/cpufreq/vexpress-spc-cpufreq.c:454:13: error:
unused variable 'cur_cluster'

Remove

cpufreq: vexpress: Drop unused variable

arm:allmodconfig fails to build with the following error.

drivers/cpufreq/vexpress-spc-cpufreq.c:454:13: error:
unused variable 'cur_cluster'

Remove the unused variable.

Fixes: bb8c26d9387f ("cpufreq: vexpress: Set CPUFREQ_IS_COOLING_DEV flag")
Cc: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Reviewed-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

show more ...

cpufreq: vexpress: Use .register_em() to register with energy model

Set the newly added .register_em() callback with
cpufreq_register_em_with_opp() to register with the EM core.

Acked-by: Sudeep Ho

cpufreq: vexpress: Use .register_em() to register with energy model

Set the newly added .register_em() callback with
cpufreq_register_em_with_opp() to register with the EM core.

Acked-by: Sudeep Holla <sudeep.holla@arm.com>
Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>

show more ...

cpufreq: vexpress: Set CPUFREQ_IS_COOLING_DEV flag

Reuse the cpufreq core's registration of cooling device by setting the
CPUFREQ_IS_COOLING_DEV flag. Set this only if bL switcher isn't enabled.

Si

cpufreq: vexpress: Set CPUFREQ_IS_COOLING_DEV flag

Reuse the cpufreq core's registration of cooling device by setting the
CPUFREQ_IS_COOLING_DEV flag. Set this only if bL switcher isn't enabled.

Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>

show more ...

cpufreq: Remove CPUFREQ_STICKY flag

During cpufreq driver's registration, if the ->init() callback for all
the CPUs fail then there is not much point in keeping the driver around
as it will only acc

cpufreq: Remove CPUFREQ_STICKY flag

During cpufreq driver's registration, if the ->init() callback for all
the CPUs fail then there is not much point in keeping the driver around
as it will only account for more of unnecessary noise, for example
cpufreq core will try to suspend/resume the driver which never got
registered properly.

The removal of such a driver is avoided if the driver carries the
CPUFREQ_STICKY flag. This was added way back [1] in 2004 and perhaps no
one should ever need it now. A lot of drivers do set this flag, probably
because they just copied it from other drivers.

This was added earlier for some platforms [2] because their cpufreq
drivers were getting registered before the CPUs were registered with
subsys framework. And hence they used to fail.

The same isn't true anymore though. The current code flow in the kernel
is:

start_kernel()
-> kernel_init()
-> kernel_init_freeable()
-> do_basic_setup()
-> driver_init()
-> cpu_dev_init()
-> subsys_system_register() //For CPUs

-> do_initcalls()
-> cpufreq_register_driver()

Clearly, the CPUs will always get registered with subsys framework
before any cpufreq driver can get probed. Remove the flag and update the
relevant drivers.

Link: https://git.kernel.org/pub/scm/linux/kernel/git/tglx/history.git/commit/include/linux/cpufreq.h?id=7cc9f0d9a1ab04cedc60d64fd8dcf7df224a3b4d # [1]
Link: https://git.kernel.org/pub/scm/linux/kernel/git/tglx/history.git/commit/arch/arm/mach-sa1100/cpu-sa1100.c?id=f59d3bbe35f6268d729f51be82af8325d62f20f5 # [2]
Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

show more ...

cpufreq: vexpress-spc: Add missing MODULE_ALIAS

This patch adds missing MODULE_ALIAS for automatic loading of this cpufreq
driver when it is compiled as an external module.

Signed-off-by: Pali Rohá

cpufreq: vexpress-spc: Add missing MODULE_ALIAS

This patch adds missing MODULE_ALIAS for automatic loading of this cpufreq
driver when it is compiled as an external module.

Signed-off-by: Pali Rohár <pali@kernel.org>
Fixes: 47ac9aa165540 ("cpufreq: arm_big_little: add vexpress SPC interface driver")
Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>

show more ...

cpufreq: vexpress-spc: Add missing MODULE_ALIAS

[ Upstream commit d15183991c2d53d7cecf27a1555c91b702cef1ea ]

This patch adds missing MODULE_ALIAS for automatic loading of this cpufreq
driver when i

cpufreq: vexpress-spc: Add missing MODULE_ALIAS

[ Upstream commit d15183991c2d53d7cecf27a1555c91b702cef1ea ]

This patch adds missing MODULE_ALIAS for automatic loading of this cpufreq
driver when it is compiled as an external module.

Signed-off-by: Pali Rohár <pali@kernel.org>
Fixes: 47ac9aa165540 ("cpufreq: arm_big_little: add vexpress SPC interface driver")
Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>

show more ...

cpufreq: move invariance setter calls in cpufreq core

To properly scale its per-entity load-tracking signals, the task scheduler
needs to be given a frequency scale factor, i.e. some image of the cu

cpufreq: move invariance setter calls in cpufreq core

To properly scale its per-entity load-tracking signals, the task scheduler
needs to be given a frequency scale factor, i.e. some image of the current
frequency the CPU is running at. Currently, this scale can be computed
either by using counters (APERF/MPERF on x86, AMU on arm64), or by
piggy-backing on the frequency selection done by cpufreq.

For the latter, drivers have to explicitly set the scale factor
themselves, despite it being purely boiler-plate code: the required
information depends entirely on the kind of frequency switch callback
implemented by the driver, i.e. either of: target_index(), target(),
fast_switch() and setpolicy().

The fitness of those callbacks with regard to driving the Frequency
Invariance Engine (FIE) is studied below:

target_index()
==============
Documentation states that the chosen frequency "must be determined by
freq_table[index].frequency". It isn't clear if it *has* to be that
frequency, or if it can use that frequency value to do some computation
that ultimately leads to a different frequency selection. All drivers
go for the former, while the vexpress-spc-cpufreq has an atypical
implementation which is handled separately.

Therefore, the hook works on the assumption the core can use
freq_table[index].frequency.

target()
=======
This has been flagged as deprecated since:

commit 9c0ebcf78fde ("cpufreq: Implement light weight ->target_index() routine")

It also doesn't have that many users:

gx-suspmod.c:439: .target = cpufreq_gx_target,
s3c24xx-cpufreq.c:428: .target = s3c_cpufreq_target,
intel_pstate.c:2528: .target = intel_cpufreq_target,
cppc_cpufreq.c:401: .target = cppc_cpufreq_set_target,
cpufreq-nforce2.c:371: .target = nforce2_target,
sh-cpufreq.c:163: .target = sh_cpufreq_target,
pcc-cpufreq.c:573: .target = pcc_cpufreq_target,

Similarly to the path taken for target_index() calls in the cpufreq core
during a frequency change, all of the drivers above will mark the end of a
frequency change by a call to cpufreq_freq_transition_end().

Therefore, cpufreq_freq_transition_end() can be used as the location for
the arch_set_freq_scale() call to potentially inform the scheduler of the
frequency change.

This change maintains the previous functionality for the drivers that
implement the target_index() callback, while also adding support for the
few drivers that implement the deprecated target() callback.

fast_switch()
=============
This callback *has* to return the frequency that was selected.

setpolicy()
===========
This callback does not have any designated way of informing what was the
end choice. But there are only two drivers using setpolicy(), and none
of them have current FIE support:

drivers/cpufreq/longrun.c:281: .setpolicy = longrun_set_policy,
drivers/cpufreq/intel_pstate.c:2215: .setpolicy = intel_pstate_set_policy,

The intel_pstate is known to use counter-driven frequency invariance.

Conclusion
==========

Given that the significant majority of current FIE enabled drivers use
callbacks that lend themselves to triggering the setting of the FIE scale
factor in a generic way, move the invariance setter calls to cpufreq core.

As a result of setting the frequency scale factor in cpufreq core, after
callbacks that lend themselves to trigger it, remove this functionality
from the driver side.

To be noted that despite marking a successful frequency change, many
cpufreq drivers will consider the new frequency as the requested
frequency, although this is might not be the one granted by the hardware.

Therefore, the call to arch_set_freq_scale() is a "best effort" one, and
it is up to the architecture if the new frequency is used in the new
frequency scale factor setting (determined by the implementation of
arch_set_freq_scale()) or eventually used by the scheduler (determined
by the implementation of arch_scale_freq_capacity()). The architecture
is in a better position to decide if it has better methods to obtain
more accurate information regarding the current frequency and use that
information instead (for example, the use of counters).

Also, the implementation to arch_set_freq_scale() will now have to handle
error conditions (current frequency == 0) in order to prevent the
overhead in cpufreq core when the default arch_set_freq_scale()
implementation is used.

Signed-off-by: Ionela Voinescu <ionela.voinescu@arm.com>
Suggested-by: Valentin Schneider <valentin.schneider@arm.com>
Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
Acked-by: Sudeep Holla <sudeep.holla@arm.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

show more ...

OPP: refactor dev_pm_opp_of_register_em() and update related drivers

The Energy Model framework supports not only CPU devices. Drop the CPU
specific interface with cpumask and add struct device. Add

OPP: refactor dev_pm_opp_of_register_em() and update related drivers

The Energy Model framework supports not only CPU devices. Drop the CPU
specific interface with cpumask and add struct device. Add also a return
value, user might use it. This new interface provides easy way to create
a simple Energy Model, which then might be used by e.g. thermal subsystem.

Acked-by: Daniel Lezcano <daniel.lezcano@linaro.org>
Signed-off-by: Lukasz Luba <lukasz.luba@arm.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

show more ...

cpufreq: vexpress-spc: Switch cpumask from topology core to OPP sharing

Since commit ca74b316df96 ("arm: Use common cpu_topology structure and
functions.") the core cpumask has to be modified during

cpufreq: vexpress-spc: Switch cpumask from topology core to OPP sharing

Since commit ca74b316df96 ("arm: Use common cpu_topology structure and
functions.") the core cpumask has to be modified during cpu hotplug
operations. So using them to set up cpufreq policy cpumask may be
incorrect as it may contain only cpus that are online at that instance.

Instead, we can use the cpumask setup by OPP library that contains all
the cpus sharing OPP table using dev_pm_opp_get_sharing_cpus.

Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
Tested-by: Dietmar Eggemann <dietmar.eggemann@arm.com>
Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>

show more ...

cpufreq: vexpress-spc: find and skip duplicates when merging frequencies

Currently the cpufreq core aborts the validation and return error
immediately when it encounter duplicate frequency table ent

cpufreq: vexpress-spc: find and skip duplicates when merging frequencies

Currently the cpufreq core aborts the validation and return error
immediately when it encounter duplicate frequency table entries.
This change was introduced long back since commit da0c6dc00c69
("cpufreq: Handle sorted frequency tables more efficiently").

However, this missed the testing with modified firmware for long time.
Inorder to make it work with default settings, we need to ensure the
merged table for bL switcher contains no duplicates. Find the duplicates
and skip them when merging the frequenct tables of A15 and A7 clusters.

Cc: Viresh Kumar <viresh.kumar@linaro.org>
Cc: "Rafael J. Wysocki" <rjw@rjwysocki.net>
Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>
Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>

show more ...

cpufreq: vexpress-spc: use macros instead of hardcoded values for cluster ids

A15 and A7 cluster identifiers are fixed to 0 and 1 respectively. There are
macros for the same and used in most of the

cpufreq: vexpress-spc: use macros instead of hardcoded values for cluster ids

A15 and A7 cluster identifiers are fixed to 0 and 1 respectively. There are
macros for the same and used in most of the places except this instance.

Lets use macros instead of hardcoded values for cluster ids even here.

Cc: Viresh Kumar <viresh.kumar@linaro.org>
Cc: "Rafael J. Wysocki" <rjw@rjwysocki.net>
Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>
Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>

show more ...

cpufreq: vexpress-spc: fix some coding style issues

Fix the following checkpatch checks/warnings:

CHECK: Unnecessary parentheses around the code
CHECK: Alignment should match open parenthesis
CHECK

cpufreq: vexpress-spc: fix some coding style issues

Fix the following checkpatch checks/warnings:

CHECK: Unnecessary parentheses around the code
CHECK: Alignment should match open parenthesis
CHECK: Prefer kernel type 'u32' over 'uint32_t'
WARNING: Missing a blank line after declarations

Acked-by: Nicolas Pitre <nico@fluxnic.net>
Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>
Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>

show more ...

cpufreq: vexpress-spc: remove lots of debug messages

This driver have been used and tested for year now and the extensive
debug/log messages in the driver are not really required anymore.
Get rid of

cpufreq: vexpress-spc: remove lots of debug messages

This driver have been used and tested for year now and the extensive
debug/log messages in the driver are not really required anymore.
Get rid of those unnecessary log messages.

Acked-by: Nicolas Pitre <nico@fluxnic.net>
Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>
Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>

show more ...

cpufreq: vexpress-spc: drop unnessary cpufreq_arm_bL_ops abstraction

cpufreq_arm_bL_ops is no longer needed after merging the generic
arm_big_little and vexpress-spc driver. Remove it along with the

cpufreq: vexpress-spc: drop unnessary cpufreq_arm_bL_ops abstraction

cpufreq_arm_bL_ops is no longer needed after merging the generic
arm_big_little and vexpress-spc driver. Remove it along with the
unused bL_cpufreq_{,un}register routines and rename some bL_*
functions to ve_spc_*.

Acked-by: Nicolas Pitre <nico@fluxnic.net>
Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>
Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>

show more ...

cpufreq: merge arm_big_little and vexpress-spc

arm_big_little cpufreq driver was designed as a generic big little
driver that could be used by any platform and make use of bL switcher.
Over years al

cpufreq: merge arm_big_little and vexpress-spc

arm_big_little cpufreq driver was designed as a generic big little
driver that could be used by any platform and make use of bL switcher.
Over years alternate solutions have been designed and merged to deal
with bL/HMP systems like EAS.

Also since no other driver made use of generic arm_big_little cpufreq
driver except Vexpress SPC, we can merge them together as vexpress-spc
driver used only on Vexpress TC2(CA15_CA7) platform.

Acked-by: Nicolas Pitre <nico@fluxnic.net>
Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>
Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>

show more ...

cpufreq: arm_big_little: make cpufreq_arm_bL_ops structures const

Make these const as they are only getting passed to the functions
bL_cpufreq_{register/unregister} having the arguments as const.

S

cpufreq: arm_big_little: make cpufreq_arm_bL_ops structures const

Make these const as they are only getting passed to the functions
bL_cpufreq_{register/unregister} having the arguments as const.

Signed-off-by: Bhumika Goyal <bhumirks@gmail.com>
Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

show more ...

cpufreq: arm_big_little: use generic OPP functions for {init, free}_opp_table

Currently when performing random CPU hot-plugs and suspend-to-ram(S2R)
on systems using arm_big_little cpufreq driver, w

cpufreq: arm_big_little: use generic OPP functions for {init, free}_opp_table

Currently when performing random CPU hot-plugs and suspend-to-ram(S2R)
on systems using arm_big_little cpufreq driver, we get warnings similar
to something like below:

cpu cpu1: _opp_add: duplicate OPPs detected. Existing: freq: 600000000,
volt: 800000, enabled: 1. New: freq: 600000000, volt: 800000, enabled: 1

This is mainly because the OPPs for the shared cpus are not set. We can
just use dev_pm_opp_of_cpumask_add_table in case the OPPs are obtained
from DT(arm_big_little_dt.c) or use dev_pm_opp_set_sharing_cpus if the
OPPs are obtained by other means like firmware(e.g. scpi-cpufreq.c)

Also now that the generic dev_pm_opp{,_of}_cpumask_remove_table can
handle removal of opp table and entries for all associated CPUs, we can
re-use dev_pm_opp{,_of}_cpumask_remove_table as free_opp_table in
cpufreq_arm_bL_ops.

This patch makes necessary changes to reuse the generic OPP functions for
{init,free}_opp_table and thereby eliminating the warnings.

Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>
Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

show more ...

cpufreq: drop owner assignment from platform_drivers

A platform_driver does not need to set an owner, it will be populated by the
driver core.

Signed-off-by: Wolfram Sang <wsa@the-dreams.de>

cpufreq: arm_big_little: add vexpress SPC interface driver

The TC2(i.e. CA15_A7) Versatile Express has external Cortex M3 based
power controller which is responsible for CPU DVFS and SPC provides
th

cpufreq: arm_big_little: add vexpress SPC interface driver

The TC2(i.e. CA15_A7) Versatile Express has external Cortex M3 based
power controller which is responsible for CPU DVFS and SPC provides
the interface for the same.

This patch adds a tiny interface driver to check if OPPs are
initialised by SPC platform code and register the arm_big_little
cpufreq driver.

Signed-off-by: Sudeep KarkadaNagesha <sudeep.karkadanagesha@arm.com>
Acked-by: Nicolas Pitre <nico@linaro.org>
Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

show more ...

cpufreq: vexpress-spc: Add missing MODULE_ALIAS

[ Upstream commit d15183991c2d53d7cecf27a1555c91b702cef1ea ]

This patch adds missing MODULE_ALIAS for automatic loading of this cpufr

cpufreq: vexpress-spc: Add missing MODULE_ALIAS

[ Upstream commit d15183991c2d53d7cecf27a1555c91b702cef1ea ]

This patch adds missing MODULE_ALIAS for automatic loading of this cpufreq
driver when it is compiled as an external module.

Signed-off-by: Pali Rohár <pali@kernel.org>
Fixes: 47ac9aa165540 ("cpufreq: arm_big_little: add vexpress SPC interface driver")
Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>

show more ...

cpufreq: move invariance setter calls in cpufreq core

To properly scale its per-entity load-tracking signals, the task scheduler
needs to be given a frequency scale factor, i.e. some ima

cpufreq: move invariance setter calls in cpufreq core

To properly scale its per-entity load-tracking signals, the task scheduler
needs to be given a frequency scale factor, i.e. some image of the current
frequency the CPU is running at. Currently, this scale can be computed
either by using counters (APERF/MPERF on x86, AMU on arm64), or by
piggy-backing on the frequency selection done by cpufreq.

For the latter, drivers have to explicitly set the scale factor
themselves, despite it being purely boiler-plate code: the required
information depends entirely on the kind of frequency switch callback
implemented by the driver, i.e. either of: target_index(), target(),
fast_switch() and setpolicy().

The fitness of those callbacks with regard to driving the Frequency
Invariance Engine (FIE) is studied below:

target_index()
==============
Documentation states that the chosen frequency "must be determined by
freq_table[index].frequency". It isn't clear if it *has* to be that
frequency, or if it can use that frequency value to do some computation
that ultimately leads to a different frequency selection. All drivers
go for the former, while the vexpress-spc-cpufreq has an atypical
implementation which is handled separately.

Therefore, the hook works on the assumption the core can use
freq_table[index].frequency.

target()
=======
This has been flagged as deprecated since:

commit 9c0ebcf78fde ("cpufreq: Implement light weight ->target_index() routine")

It also doesn't have that many users:

gx-suspmod.c:439: .target = cpufreq_gx_target,
s3c24xx-cpufreq.c:428: .target = s3c_cpufreq_target,
intel_pstate.c:2528: .target = intel_cpufreq_target,
cppc_cpufreq.c:401: .target = cppc_cpufreq_set_target,
cpufreq-nforce2.c:371: .target = nforce2_target,
sh-cpufreq.c:163: .target = sh_cpufreq_target,
pcc-cpufreq.c:573: .target = pcc_cpufreq_target,

Similarly to the path taken for target_index() calls in the cpufreq core
during a frequency change, all of the drivers above will mark the end of a
frequency change by a call to cpufreq_freq_transition_end().

Therefore, cpufreq_freq_transition_end() can be used as the location for
the arch_set_freq_scale() call to potentially inform the scheduler of the
frequency change.

This change maintains the previous functionality for the drivers that
implement the target_index() callback, while also adding support for the
few drivers that implement the deprecated target() callback.

fast_switch()
=============
This callback *has* to return the frequency that was selected.

setpolicy()
===========
This callback does not have any designated way of informing what was the
end choice. But there are only two drivers using setpolicy(), and none
of them have current FIE support:

drivers/cpufreq/longrun.c:281: .setpolicy = longrun_set_policy,
drivers/cpufreq/intel_pstate.c:2215: .setpolicy = intel_pstate_set_policy,

The intel_pstate is known to use counter-driven frequency invariance.

Conclusion
==========

Given that the significant majority of current FIE enabled drivers use
callbacks that lend themselves to triggering the setting of the FIE scale
factor in a generic way, move the invariance setter calls to cpufreq core.

As a result of setting the frequency scale factor in cpufreq core, after
callbacks that lend themselves to trigger it, remove this functionality
from the driver side.

To be noted that despite marking a successful frequency change, many
cpufreq drivers will consider the new frequency as the requested
frequency, although this is might not be the one granted by the hardware.

Therefore, the call to arch_set_freq_scale() is a "best effort" one, and
it is up to the architecture if the new frequency is used in the new
frequency scale factor setting (determined by the implementation of
arch_set_freq_scale()) or eventually used by the scheduler (determined
by the implementation of arch_scale_freq_capacity()). The architecture
is in a better position to decide if it has better methods to obtain
more accurate information regarding the current frequency and use that
information instead (for example, the use of counters).

Also, the implementation to arch_set_freq_scale() will now have to handle
error conditions (current frequency == 0) in order to prevent the
overhead in cpufreq core when the default arch_set_freq_scale()
implementation is used.

Signed-off-by: Ionela Voinescu <ionela.voinescu@arm.com>
Suggested-by: Valentin Schneider <valentin.schneider@arm.com>
Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
Acked-by: Sudeep Holla <sudeep.holla@arm.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

show more ...

OPP: refactor dev_pm_opp_of_register_em() and update related drivers

The Energy Model framework supports not only CPU devices. Drop the CPU
specific interface with cpumask and add struct

OPP: refactor dev_pm_opp_of_register_em() and update related drivers

The Energy Model framework supports not only CPU devices. Drop the CPU
specific interface with cpumask and add struct device. Add also a return
value, user might use it. This new interface provides easy way to create
a simple Energy Model, which then might be used by e.g. thermal subsystem.

Acked-by: Daniel Lezcano <daniel.lezcano@linaro.org>
Signed-off-by: Lukasz Luba <lukasz.luba@arm.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

show more ...