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authorLinus Torvalds <torvalds@linux-foundation.org>2018-01-29 09:47:41 -0800
committerLinus Torvalds <torvalds@linux-foundation.org>2018-01-29 09:47:41 -0800
commit7f3fdd40a7dfaa7405185250974b0fabd08c1f8b (patch)
tree7451aae06a883478d380fe03f7d817d0e3232e94 /Documentation/thermal/cpu-cooling-api.txt
parent1c1f395b2873f59830979cf82324fbf00edfb80c (diff)
parentee43730d65155c5b3c3d0531f11daf59f8f42a73 (diff)
Merge tag 'pm-4.16-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm
Pull power management updates from Rafael Wysocki: "This includes some infrastructure changes in the PM core, mostly related to integration between runtime PM and system-wide suspend and hibernation, plus some driver changes depending on them and fixes for issues in that area which have become quite apparent recently. Also included are changes making more x86-based systems use the Low Power Sleep S0 _DSM interface by default, which turned out to be necessary to handle power button wakeups from suspend-to-idle on Surface Pro3. On the cpufreq front we have fixes and cleanups in the core, some new hardware support, driver updates and the removal of some unused code from the CPU cooling thermal driver. Apart from this, the Operating Performance Points (OPP) framework is prepared to be used with power domains in the future and there is a usual bunch of assorted fixes and cleanups. Specifics: - Define a PM driver flag allowing drivers to request that their devices be left in suspend after system-wide transitions to the working state if possible and add support for it to the PCI bus type and the ACPI PM domain (Rafael Wysocki). - Make the PM core carry out optimizations for devices with driver PM flags set in some cases and make a few drivers set those flags (Rafael Wysocki). - Fix and clean up wrapper routines allowing runtime PM device callbacks to be re-used for system-wide PM, change the generic power domains (genpd) framework to stop using those routines incorrectly and fix up a driver depending on that behavior of genpd (Rafael Wysocki, Ulf Hansson, Geert Uytterhoeven). - Fix and clean up the PM core's device wakeup framework and re-factor system-wide PM core code related to device wakeup (Rafael Wysocki, Ulf Hansson, Brian Norris). - Make more x86-based systems use the Low Power Sleep S0 _DSM interface by default (to fix power button wakeup from suspend-to-idle on Surface Pro3) and add a kernel command line switch to tell it to ignore the system sleep blacklist in the ACPI core (Rafael Wysocki). - Fix a race condition related to cpufreq governor module removal and clean up the governor management code in the cpufreq core (Rafael Wysocki). - Drop the unused generic code related to the handling of the static power energy usage model in the CPU cooling thermal driver along with the corresponding documentation (Viresh Kumar). - Add mt2712 support to the Mediatek cpufreq driver (Andrew-sh Cheng). - Add a new operating point to the imx6ul and imx6q cpufreq drivers and switch the latter to using clk_bulk_get() (Anson Huang, Dong Aisheng). - Add support for multiple regulators to the TI cpufreq driver along with a new DT binding related to that and clean up that driver somewhat (Dave Gerlach). - Fix a powernv cpufreq driver regression leading to incorrect CPU frequency reporting, fix that driver to deal with non-continguous P-states correctly and clean it up (Gautham Shenoy, Shilpasri Bhat). - Add support for frequency scaling on Armada 37xx SoCs through the generic DT cpufreq driver (Gregory CLEMENT). - Fix error code paths in the mvebu cpufreq driver (Gregory CLEMENT). - Fix a transition delay setting regression in the longhaul cpufreq driver (Viresh Kumar). - Add Skylake X (server) support to the intel_pstate cpufreq driver and clean up that driver somewhat (Srinivas Pandruvada). - Clean up the cpufreq statistics collection code (Viresh Kumar). - Drop cluster terminology and dependency on physical_package_id from the PSCI driver and drop dependency on arm_big_little from the SCPI cpufreq driver (Sudeep Holla). - Add support for system-wide suspend and resume to the RAPL power capping driver and drop a redundant semicolon from it (Zhen Han, Luis de Bethencourt). - Make SPI domain validation (in the SCSI SPI transport driver) and system-wide suspend mutually exclusive as they rely on the same underlying mechanism and cannot be carried out at the same time (Bart Van Assche). - Fix the computation of the amount of memory to preallocate in the hibernation core and clean up one function in there (Rainer Fiebig, Kyungsik Lee). - Prepare the Operating Performance Points (OPP) framework for being used with power domains and clean up one function in it (Viresh Kumar, Wei Yongjun). - Clean up the generic sysfs interface for device PM (Andy Shevchenko). - Fix several minor issues in power management frameworks and clean them up a bit (Arvind Yadav, Bjorn Andersson, Geert Uytterhoeven, Gustavo Silva, Julia Lawall, Luis de Bethencourt, Paul Gortmaker, Sergey Senozhatsky, gaurav jindal). - Make it easier to disable PM via Kconfig (Mark Brown). - Clean up the cpupower and intel_pstate_tracer utilities (Doug Smythies, Laura Abbott)" * tag 'pm-4.16-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm: (89 commits) PCI / PM: Remove spurious semicolon cpufreq: scpi: remove arm_big_little dependency drivers: psci: remove cluster terminology and dependency on physical_package_id powercap: intel_rapl: Fix trailing semicolon dmaengine: rcar-dmac: Make DMAC reinit during system resume explicit PM / runtime: Allow no callbacks in pm_runtime_force_suspend|resume() PM / hibernate: Drop unused parameter of enough_swap PM / runtime: Check ignore_children in pm_runtime_need_not_resume() PM / runtime: Rework pm_runtime_force_suspend/resume() PM / genpd: Stop/start devices without pm_runtime_force_suspend/resume() cpufreq: powernv: Dont assume distinct pstate values for nominal and pmin cpufreq: intel_pstate: Add Skylake servers support cpufreq: intel_pstate: Replace bxt_funcs with core_funcs platform/x86: surfacepro3: Support for wakeup from suspend-to-idle ACPI / PM: Use Low Power S0 Idle on more systems PM / wakeup: Print warn if device gets enabled as wakeup source during sleep PM / domains: Don't skip driver's ->suspend|resume_noirq() callbacks PM / core: Propagate wakeup_path status flag in __device_suspend_late() PM / core: Re-structure code for clearing the direct_complete flag powercap: add suspend and resume mechanism for SOC power limit ...
Diffstat (limited to 'Documentation/thermal/cpu-cooling-api.txt')
-rw-r--r--Documentation/thermal/cpu-cooling-api.txt115
1 files changed, 5 insertions, 110 deletions
diff --git a/Documentation/thermal/cpu-cooling-api.txt b/Documentation/thermal/cpu-cooling-api.txt
index 71653584cd03..7df567eaea1a 100644
--- a/Documentation/thermal/cpu-cooling-api.txt
+++ b/Documentation/thermal/cpu-cooling-api.txt
@@ -26,39 +26,16 @@ the user. The registration APIs returns the cooling device pointer.
clip_cpus: cpumask of cpus where the frequency constraints will happen.
1.1.2 struct thermal_cooling_device *of_cpufreq_cooling_register(
- struct device_node *np, const struct cpumask *clip_cpus)
+ struct cpufreq_policy *policy)
This interface function registers the cpufreq cooling device with
the name "thermal-cpufreq-%x" linking it with a device tree node, in
order to bind it via the thermal DT code. This api can support multiple
instances of cpufreq cooling devices.
- np: pointer to the cooling device device tree node
- clip_cpus: cpumask of cpus where the frequency constraints will happen.
+ policy: CPUFreq policy.
-1.1.3 struct thermal_cooling_device *cpufreq_power_cooling_register(
- const struct cpumask *clip_cpus, u32 capacitance,
- get_static_t plat_static_func)
-
-Similar to cpufreq_cooling_register, this function registers a cpufreq
-cooling device. Using this function, the cooling device will
-implement the power extensions by using a simple cpu power model. The
-cpus must have registered their OPPs using the OPP library.
-
-The additional parameters are needed for the power model (See 2. Power
-models). "capacitance" is the dynamic power coefficient (See 2.1
-Dynamic power). "plat_static_func" is a function to calculate the
-static power consumed by these cpus (See 2.2 Static power).
-
-1.1.4 struct thermal_cooling_device *of_cpufreq_power_cooling_register(
- struct device_node *np, const struct cpumask *clip_cpus, u32 capacitance,
- get_static_t plat_static_func)
-
-Similar to cpufreq_power_cooling_register, this function register a
-cpufreq cooling device with power extensions using the device tree
-information supplied by the np parameter.
-
-1.1.5 void cpufreq_cooling_unregister(struct thermal_cooling_device *cdev)
+1.1.3 void cpufreq_cooling_unregister(struct thermal_cooling_device *cdev)
This interface function unregisters the "thermal-cpufreq-%x" cooling device.
@@ -67,20 +44,14 @@ information supplied by the np parameter.
2. Power models
The power API registration functions provide a simple power model for
-CPUs. The current power is calculated as dynamic + (optionally)
-static power. This power model requires that the operating-points of
+CPUs. The current power is calculated as dynamic power (static power isn't
+supported currently). This power model requires that the operating-points of
the CPUs are registered using the kernel's opp library and the
`cpufreq_frequency_table` is assigned to the `struct device` of the
cpu. If you are using CONFIG_CPUFREQ_DT then the
`cpufreq_frequency_table` should already be assigned to the cpu
device.
-The `plat_static_func` parameter of `cpufreq_power_cooling_register()`
-and `of_cpufreq_power_cooling_register()` is optional. If you don't
-provide it, only dynamic power will be considered.
-
-2.1 Dynamic power
-
The dynamic power consumption of a processor depends on many factors.
For a given processor implementation the primary factors are:
@@ -119,79 +90,3 @@ mW/MHz/uVolt^2. Typical values for mobile CPUs might lie in range
from 100 to 500. For reference, the approximate values for the SoC in
ARM's Juno Development Platform are 530 for the Cortex-A57 cluster and
140 for the Cortex-A53 cluster.
-
-
-2.2 Static power
-
-Static leakage power consumption depends on a number of factors. For a
-given circuit implementation the primary factors are:
-
-- Time the circuit spends in each 'power state'
-- Temperature
-- Operating voltage
-- Process grade
-
-The time the circuit spends in each 'power state' for a given
-evaluation period at first order means OFF or ON. However,
-'retention' states can also be supported that reduce power during
-inactive periods without loss of context.
-
-Note: The visibility of state entries to the OS can vary, according to
-platform specifics, and this can then impact the accuracy of a model
-based on OS state information alone. It might be possible in some
-cases to extract more accurate information from system resources.
-
-The temperature, operating voltage and process 'grade' (slow to fast)
-of the circuit are all significant factors in static leakage power
-consumption. All of these have complex relationships to static power.
-
-Circuit implementation specific factors include the chosen silicon
-process as well as the type, number and size of transistors in both
-the logic gates and any RAM elements included.
-
-The static power consumption modelling must take into account the
-power managed regions that are implemented. Taking the example of an
-ARM processor cluster, the modelling would take into account whether
-each CPU can be powered OFF separately or if only a single power
-region is implemented for the complete cluster.
-
-In one view, there are others, a static power consumption model can
-then start from a set of reference values for each power managed
-region (e.g. CPU, Cluster/L2) in each state (e.g. ON, OFF) at an
-arbitrary process grade, voltage and temperature point. These values
-are then scaled for all of the following: the time in each state, the
-process grade, the current temperature and the operating voltage.
-However, since both implementation specific and complex relationships
-dominate the estimate, the appropriate interface to the model from the
-cpu cooling device is to provide a function callback that calculates
-the static power in this platform. When registering the cpu cooling
-device pass a function pointer that follows the `get_static_t`
-prototype:
-
- int plat_get_static(cpumask_t *cpumask, int interval,
- unsigned long voltage, u32 &power);
-
-`cpumask` is the cpumask of the cpus involved in the calculation.
-`voltage` is the voltage at which they are operating. The function
-should calculate the average static power for the last `interval`
-milliseconds. It returns 0 on success, -E* on error. If it
-succeeds, it should store the static power in `power`. Reading the
-temperature of the cpus described by `cpumask` is left for
-plat_get_static() to do as the platform knows best which thermal
-sensor is closest to the cpu.
-
-If `plat_static_func` is NULL, static power is considered to be
-negligible for this platform and only dynamic power is considered.
-
-The platform specific callback can then use any combination of tables
-and/or equations to permute the estimated value. Process grade
-information is not passed to the model since access to such data, from
-on-chip measurement capability or manufacture time data, is platform
-specific.
-
-Note: the significance of static power for CPUs in comparison to
-dynamic power is highly dependent on implementation. Given the
-potential complexity in implementation, the importance and accuracy of
-its inclusion when using cpu cooling devices should be assessed on a
-case by case basis.
-