From 91cfbd4ee0875f8a826731983378670012ba6e01 Mon Sep 17 00:00:00 2001 From: Thomas Abraham Date: Fri, 27 Jan 2012 15:25:00 +0900 Subject: ARM: EXYNOS: Hook up power domains to generic power domain infrastructure Add support for generic power domain for Exynos4 platforms and remove the Samsung specific power domain control for Exynos4. The generic power domain infrastructure is used to control the power domains available on Exynos4. For non-dt platforms, the power domains are statically instantiated. For dt platforms, the power domain nodes found in the device tree are instantiated. Cc: Kyungmin Park Cc: Rob Herring Cc: Grant Likely Signed-off-by: Thomas Abraham Acked-by: Rafael J. Wysocki Signed-off-by: Kukjin Kim --- .../devicetree/bindings/arm/exynos/power_domain.txt | 21 +++++++++++++++++++++ 1 file changed, 21 insertions(+) create mode 100644 Documentation/devicetree/bindings/arm/exynos/power_domain.txt (limited to 'Documentation') diff --git a/Documentation/devicetree/bindings/arm/exynos/power_domain.txt b/Documentation/devicetree/bindings/arm/exynos/power_domain.txt new file mode 100644 index 000000000000..6528e215c5fe --- /dev/null +++ b/Documentation/devicetree/bindings/arm/exynos/power_domain.txt @@ -0,0 +1,21 @@ +* Samsung Exynos Power Domains + +Exynos processors include support for multiple power domains which are used +to gate power to one or more peripherals on the processor. + +Required Properties: +- compatiable: should be one of the following. + * samsung,exynos4210-pd - for exynos4210 type power domain. +- reg: physical base address of the controller and length of memory mapped + region. + +Optional Properties: +- samsung,exynos4210-pd-off: Specifies that the power domain is in turned-off + state during boot and remains to be turned-off until explicitly turned-on. + +Example: + + lcd0: power-domain-lcd0 { + compatible = "samsung,exynos4210-pd"; + reg = <0x10023C00 0x10>; + }; -- cgit v1.2.2 From cf579dfb82550e34de7ccf3ef090d8b834ccd3a9 Mon Sep 17 00:00:00 2001 From: "Rafael J. Wysocki" Date: Sun, 29 Jan 2012 20:38:29 +0100 Subject: PM / Sleep: Introduce "late suspend" and "early resume" of devices The current device suspend/resume phases during system-wide power transitions appear to be insufficient for some platforms that want to use the same callback routines for saving device states and related operations during runtime suspend/resume as well as during system suspend/resume. In principle, they could point their .suspend_noirq() and .resume_noirq() to the same callback routines as their .runtime_suspend() and .runtime_resume(), respectively, but at least some of them require device interrupts to be enabled while the code in those routines is running. It also makes sense to have device suspend-resume callbacks that will be executed with runtime PM disabled and with device interrupts enabled in case someone needs to run some special code in that context during system-wide power transitions. Apart from this, .suspend_noirq() and .resume_noirq() were introduced as a workaround for drivers using shared interrupts and failing to prevent their interrupt handlers from accessing suspended hardware. It appears to be better not to use them for other porposes, or we may have to deal with some serious confusion (which seems to be happening already). For the above reasons, introduce new device suspend/resume phases, "late suspend" and "early resume" (and analogously for hibernation) whose callback will be executed with runtime PM disabled and with device interrupts enabled and whose callback pointers generally may point to runtime suspend/resume routines. Signed-off-by: Rafael J. Wysocki Reviewed-by: Mark Brown Reviewed-by: Kevin Hilman --- Documentation/power/devices.txt | 93 +++++++++++++++++++++++++++-------------- 1 file changed, 61 insertions(+), 32 deletions(-) (limited to 'Documentation') diff --git a/Documentation/power/devices.txt b/Documentation/power/devices.txt index 20af7def23c8..872815cd41d3 100644 --- a/Documentation/power/devices.txt +++ b/Documentation/power/devices.txt @@ -96,6 +96,12 @@ struct dev_pm_ops { int (*thaw)(struct device *dev); int (*poweroff)(struct device *dev); int (*restore)(struct device *dev); + int (*suspend_late)(struct device *dev); + int (*resume_early)(struct device *dev); + int (*freeze_late)(struct device *dev); + int (*thaw_early)(struct device *dev); + int (*poweroff_late)(struct device *dev); + int (*restore_early)(struct device *dev); int (*suspend_noirq)(struct device *dev); int (*resume_noirq)(struct device *dev); int (*freeze_noirq)(struct device *dev); @@ -305,7 +311,7 @@ Entering System Suspend ----------------------- When the system goes into the standby or memory sleep state, the phases are: - prepare, suspend, suspend_noirq. + prepare, suspend, suspend_late, suspend_noirq. 1. The prepare phase is meant to prevent races by preventing new devices from being registered; the PM core would never know that all the @@ -324,7 +330,12 @@ When the system goes into the standby or memory sleep state, the phases are: appropriate low-power state, depending on the bus type the device is on, and they may enable wakeup events. - 3. The suspend_noirq phase occurs after IRQ handlers have been disabled, + 3 For a number of devices it is convenient to split suspend into the + "quiesce device" and "save device state" phases, in which cases + suspend_late is meant to do the latter. It is always executed after + runtime power management has been disabled for all devices. + + 4. The suspend_noirq phase occurs after IRQ handlers have been disabled, which means that the driver's interrupt handler will not be called while the callback method is running. The methods should save the values of the device's registers that weren't saved previously and finally put the @@ -359,7 +370,7 @@ Leaving System Suspend ---------------------- When resuming from standby or memory sleep, the phases are: - resume_noirq, resume, complete. + resume_noirq, resume_early, resume, complete. 1. The resume_noirq callback methods should perform any actions needed before the driver's interrupt handlers are invoked. This generally @@ -375,14 +386,18 @@ When resuming from standby or memory sleep, the phases are: device driver's ->pm.resume_noirq() method to perform device-specific actions. - 2. The resume methods should bring the the device back to its operating + 2. The resume_early methods should prepare devices for the execution of + the resume methods. This generally involves undoing the actions of the + preceding suspend_late phase. + + 3 The resume methods should bring the the device back to its operating state, so that it can perform normal I/O. This generally involves undoing the actions of the suspend phase. - 3. The complete phase uses only a bus callback. The method should undo the - actions of the prepare phase. Note, however, that new children may be - registered below the device as soon as the resume callbacks occur; it's - not necessary to wait until the complete phase. + 4. The complete phase should undo the actions of the prepare phase. Note, + however, that new children may be registered below the device as soon as + the resume callbacks occur; it's not necessary to wait until the + complete phase. At the end of these phases, drivers should be as functional as they were before suspending: I/O can be performed using DMA and IRQs, and the relevant clocks are @@ -429,8 +444,8 @@ an image of the system memory while everything is stable, reactivate all devices (thaw), write the image to permanent storage, and finally shut down the system (poweroff). The phases used to accomplish this are: - prepare, freeze, freeze_noirq, thaw_noirq, thaw, complete, - prepare, poweroff, poweroff_noirq + prepare, freeze, freeze_late, freeze_noirq, thaw_noirq, thaw_early, + thaw, complete, prepare, poweroff, poweroff_late, poweroff_noirq 1. The prepare phase is discussed in the "Entering System Suspend" section above. @@ -441,7 +456,11 @@ system (poweroff). The phases used to accomplish this are: save time it's best not to do so. Also, the device should not be prepared to generate wakeup events. - 3. The freeze_noirq phase is analogous to the suspend_noirq phase discussed + 3. The freeze_late phase is analogous to the suspend_late phase described + above, except that the device should not be put in a low-power state and + should not be allowed to generate wakeup events by it. + + 4. The freeze_noirq phase is analogous to the suspend_noirq phase discussed above, except again that the device should not be put in a low-power state and should not be allowed to generate wakeup events. @@ -449,15 +468,19 @@ At this point the system image is created. All devices should be inactive and the contents of memory should remain undisturbed while this happens, so that the image forms an atomic snapshot of the system state. - 4. The thaw_noirq phase is analogous to the resume_noirq phase discussed + 5. The thaw_noirq phase is analogous to the resume_noirq phase discussed above. The main difference is that its methods can assume the device is in the same state as at the end of the freeze_noirq phase. - 5. The thaw phase is analogous to the resume phase discussed above. Its + 6. The thaw_early phase is analogous to the resume_early phase described + above. Its methods should undo the actions of the preceding + freeze_late, if necessary. + + 7. The thaw phase is analogous to the resume phase discussed above. Its methods should bring the device back to an operating state, so that it can be used for saving the image if necessary. - 6. The complete phase is discussed in the "Leaving System Suspend" section + 8. The complete phase is discussed in the "Leaving System Suspend" section above. At this point the system image is saved, and the devices then need to be @@ -465,16 +488,19 @@ prepared for the upcoming system shutdown. This is much like suspending them before putting the system into the standby or memory sleep state, and the phases are similar. - 7. The prepare phase is discussed above. + 9. The prepare phase is discussed above. + + 10. The poweroff phase is analogous to the suspend phase. - 8. The poweroff phase is analogous to the suspend phase. + 11. The poweroff_late phase is analogous to the suspend_late phase. - 9. The poweroff_noirq phase is analogous to the suspend_noirq phase. + 12. The poweroff_noirq phase is analogous to the suspend_noirq phase. -The poweroff and poweroff_noirq callbacks should do essentially the same things -as the suspend and suspend_noirq callbacks. The only notable difference is that -they need not store the device register values, because the registers should -already have been stored during the freeze or freeze_noirq phases. +The poweroff, poweroff_late and poweroff_noirq callbacks should do essentially +the same things as the suspend, suspend_late and suspend_noirq callbacks, +respectively. The only notable difference is that they need not store the +device register values, because the registers should already have been stored +during the freeze, freeze_late or freeze_noirq phases. Leaving Hibernation @@ -518,22 +544,25 @@ To achieve this, the image kernel must restore the devices' pre-hibernation functionality. The operation is much like waking up from the memory sleep state, although it involves different phases: - restore_noirq, restore, complete + restore_noirq, restore_early, restore, complete 1. The restore_noirq phase is analogous to the resume_noirq phase. - 2. The restore phase is analogous to the resume phase. + 2. The restore_early phase is analogous to the resume_early phase. + + 3. The restore phase is analogous to the resume phase. - 3. The complete phase is discussed above. + 4. The complete phase is discussed above. -The main difference from resume[_noirq] is that restore[_noirq] must assume the -device has been accessed and reconfigured by the boot loader or the boot kernel. -Consequently the state of the device may be different from the state remembered -from the freeze and freeze_noirq phases. The device may even need to be reset -and completely re-initialized. In many cases this difference doesn't matter, so -the resume[_noirq] and restore[_norq] method pointers can be set to the same -routines. Nevertheless, different callback pointers are used in case there is a -situation where it actually matters. +The main difference from resume[_early|_noirq] is that restore[_early|_noirq] +must assume the device has been accessed and reconfigured by the boot loader or +the boot kernel. Consequently the state of the device may be different from the +state remembered from the freeze, freeze_late and freeze_noirq phases. The +device may even need to be reset and completely re-initialized. In many cases +this difference doesn't matter, so the resume[_early|_noirq] and +restore[_early|_norq] method pointers can be set to the same routines. +Nevertheless, different callback pointers are used in case there is a situation +where it actually does matter. Device Power Management Domains -- cgit v1.2.2 From 9045a05044268b075c13bb0284601b24959dc3c6 Mon Sep 17 00:00:00 2001 From: "Srivatsa S. Bhat" Date: Sat, 4 Feb 2012 22:26:26 +0100 Subject: PM / Freezer / Docs: Document the beauty of freeze/thaw semantics The way the different freeze/thaw functions encapsulate each other are quite lovely from a design point of view. And as a side-effect, the way in which they are invoked (cleaning up on failure for example) differs significantly from how usual functions are dealt with. This is because of the underlying semantics that govern the freezing and thawing of various tasks. This subtle aspect that differentiates these functions from the rest, is worth documenting. Many thanks to Tejun Heo for providing enlightenment on this topic. Signed-off-by: Srivatsa S. Bhat Signed-off-by: Rafael J. Wysocki --- Documentation/power/freezing-of-tasks.txt | 21 +++++++++++++++++++++ 1 file changed, 21 insertions(+) (limited to 'Documentation') diff --git a/Documentation/power/freezing-of-tasks.txt b/Documentation/power/freezing-of-tasks.txt index ebd7490ef1df..ec715cd78fbb 100644 --- a/Documentation/power/freezing-of-tasks.txt +++ b/Documentation/power/freezing-of-tasks.txt @@ -63,6 +63,27 @@ devices have been reinitialized, the function thaw_processes() is called in order to clear the PF_FROZEN flag for each frozen task. Then, the tasks that have been frozen leave __refrigerator() and continue running. + +Rationale behind the functions dealing with freezing and thawing of tasks: +------------------------------------------------------------------------- + +freeze_processes(): + - freezes only userspace tasks + +freeze_kernel_threads(): + - freezes all tasks (including kernel threads) because we can't freeze + kernel threads without freezing userspace tasks + +thaw_kernel_threads(): + - thaws only kernel threads; this is particularly useful if we need to do + anything special in between thawing of kernel threads and thawing of + userspace tasks, or if we want to postpone the thawing of userspace tasks + +thaw_processes(): + - thaws all tasks (including kernel threads) because we can't thaw userspace + tasks without thawing kernel threads + + III. Which kernel threads are freezable? Kernel threads are not freezable by default. However, a kernel thread may clear -- cgit v1.2.2 From 85dc0b8a4019e38ad4fd0c008f89a5c241805ac2 Mon Sep 17 00:00:00 2001 From: "Rafael J. Wysocki" Date: Tue, 13 Mar 2012 01:01:39 +0100 Subject: PM / QoS: Make it possible to expose PM QoS latency constraints A runtime suspend of a device (e.g. an MMC controller) belonging to a power domain or, in a more complicated scenario, a runtime suspend of another device in the same power domain, may cause power to be removed from the entire domain. In that case, the amount of time necessary to runtime-resume the given device (e.g. the MMC controller) is often substantially greater than the time needed to run its driver's runtime resume callback. That may hurt performance in some situations, because user data may need to wait for the device to become operational, so we should make it possible to prevent that from happening. For this reason, introduce a new sysfs attribute for devices, power/pm_qos_resume_latency_us, allowing user space to specify the upper bound of the time necessary to bring the (runtime-suspended) device up after the resume of it has been requested. However, make that attribute appear only for the devices whose drivers declare support for it by calling the (new) dev_pm_qos_expose_latency_limit() helper function with the appropriate initial value of the attribute. Signed-off-by: Rafael J. Wysocki Reviewed-by: Kevin Hilman Reviewed-by: Mark Brown Acked-by: Linus Walleij --- Documentation/ABI/testing/sysfs-devices-power | 18 ++++++++++++++++++ 1 file changed, 18 insertions(+) (limited to 'Documentation') diff --git a/Documentation/ABI/testing/sysfs-devices-power b/Documentation/ABI/testing/sysfs-devices-power index 8ffbc25376a0..840f7d64d483 100644 --- a/Documentation/ABI/testing/sysfs-devices-power +++ b/Documentation/ABI/testing/sysfs-devices-power @@ -165,3 +165,21 @@ Description: Not all drivers support this attribute. If it isn't supported, attempts to read or write it will yield I/O errors. + +What: /sys/devices/.../power/pm_qos_latency_us +Date: March 2012 +Contact: Rafael J. Wysocki +Description: + The /sys/devices/.../power/pm_qos_resume_latency_us attribute + contains the PM QoS resume latency limit for the given device, + which is the maximum allowed time it can take to resume the + device, after it has been suspended at run time, from a resume + request to the moment the device will be ready to process I/O, + in microseconds. If it is equal to 0, however, this means that + the PM QoS resume latency may be arbitrary. + + Not all drivers support this attribute. If it isn't supported, + it is not present. + + This attribute has no effect on system-wide suspend/resume and + hibernation. -- cgit v1.2.2