linux-stable/include/linux/pm_qos.h

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#ifndef _LINUX_PM_QOS_H
#define _LINUX_PM_QOS_H
pm qos infrastructure and interface The following patch is a generalization of the latency.c implementation done by Arjan last year. It provides infrastructure for more than one parameter, and exposes a user mode interface for processes to register pm_qos expectations of processes. This interface provides a kernel and user mode interface for registering performance expectations by drivers, subsystems and user space applications on one of the parameters. Currently we have {cpu_dma_latency, network_latency, network_throughput} as the initial set of pm_qos parameters. The infrastructure exposes multiple misc device nodes one per implemented parameter. The set of parameters implement is defined by pm_qos_power_init() and pm_qos_params.h. This is done because having the available parameters being runtime configurable or changeable from a driver was seen as too easy to abuse. For each parameter a list of performance requirements is maintained along with an aggregated target value. The aggregated target value is updated with changes to the requirement list or elements of the list. Typically the aggregated target value is simply the max or min of the requirement values held in the parameter list elements. >From kernel mode the use of this interface is simple: pm_qos_add_requirement(param_id, name, target_value): Will insert a named element in the list for that identified PM_QOS parameter with the target value. Upon change to this list the new target is recomputed and any registered notifiers are called only if the target value is now different. pm_qos_update_requirement(param_id, name, new_target_value): Will search the list identified by the param_id for the named list element and then update its target value, calling the notification tree if the aggregated target is changed. with that name is already registered. pm_qos_remove_requirement(param_id, name): Will search the identified list for the named element and remove it, after removal it will update the aggregate target and call the notification tree if the target was changed as a result of removing the named requirement. >From user mode: Only processes can register a pm_qos requirement. To provide for automatic cleanup for process the interface requires the process to register its parameter requirements in the following way: To register the default pm_qos target for the specific parameter, the process must open one of /dev/[cpu_dma_latency, network_latency, network_throughput] As long as the device node is held open that process has a registered requirement on the parameter. The name of the requirement is "process_<PID>" derived from the current->pid from within the open system call. To change the requested target value the process needs to write a s32 value to the open device node. This translates to a pm_qos_update_requirement call. To remove the user mode request for a target value simply close the device node. [akpm@linux-foundation.org: fix warnings] [akpm@linux-foundation.org: fix build] [akpm@linux-foundation.org: fix build again] [akpm@linux-foundation.org: coding-style fixes] Signed-off-by: mark gross <mgross@linux.intel.com> Cc: "John W. Linville" <linville@tuxdriver.com> Cc: Len Brown <lenb@kernel.org> Cc: Jaroslav Kysela <perex@suse.cz> Cc: Takashi Iwai <tiwai@suse.de> Cc: Arjan van de Ven <arjan@infradead.org> Cc: Venki Pallipadi <venkatesh.pallipadi@intel.com> Cc: Adam Belay <abelay@novell.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-02-05 06:30:08 +00:00
/* interface for the pm_qos_power infrastructure of the linux kernel.
*
* Mark Gross <mgross@linux.intel.com>
pm qos infrastructure and interface The following patch is a generalization of the latency.c implementation done by Arjan last year. It provides infrastructure for more than one parameter, and exposes a user mode interface for processes to register pm_qos expectations of processes. This interface provides a kernel and user mode interface for registering performance expectations by drivers, subsystems and user space applications on one of the parameters. Currently we have {cpu_dma_latency, network_latency, network_throughput} as the initial set of pm_qos parameters. The infrastructure exposes multiple misc device nodes one per implemented parameter. The set of parameters implement is defined by pm_qos_power_init() and pm_qos_params.h. This is done because having the available parameters being runtime configurable or changeable from a driver was seen as too easy to abuse. For each parameter a list of performance requirements is maintained along with an aggregated target value. The aggregated target value is updated with changes to the requirement list or elements of the list. Typically the aggregated target value is simply the max or min of the requirement values held in the parameter list elements. >From kernel mode the use of this interface is simple: pm_qos_add_requirement(param_id, name, target_value): Will insert a named element in the list for that identified PM_QOS parameter with the target value. Upon change to this list the new target is recomputed and any registered notifiers are called only if the target value is now different. pm_qos_update_requirement(param_id, name, new_target_value): Will search the list identified by the param_id for the named list element and then update its target value, calling the notification tree if the aggregated target is changed. with that name is already registered. pm_qos_remove_requirement(param_id, name): Will search the identified list for the named element and remove it, after removal it will update the aggregate target and call the notification tree if the target was changed as a result of removing the named requirement. >From user mode: Only processes can register a pm_qos requirement. To provide for automatic cleanup for process the interface requires the process to register its parameter requirements in the following way: To register the default pm_qos target for the specific parameter, the process must open one of /dev/[cpu_dma_latency, network_latency, network_throughput] As long as the device node is held open that process has a registered requirement on the parameter. The name of the requirement is "process_<PID>" derived from the current->pid from within the open system call. To change the requested target value the process needs to write a s32 value to the open device node. This translates to a pm_qos_update_requirement call. To remove the user mode request for a target value simply close the device node. [akpm@linux-foundation.org: fix warnings] [akpm@linux-foundation.org: fix build] [akpm@linux-foundation.org: fix build again] [akpm@linux-foundation.org: coding-style fixes] Signed-off-by: mark gross <mgross@linux.intel.com> Cc: "John W. Linville" <linville@tuxdriver.com> Cc: Len Brown <lenb@kernel.org> Cc: Jaroslav Kysela <perex@suse.cz> Cc: Takashi Iwai <tiwai@suse.de> Cc: Arjan van de Ven <arjan@infradead.org> Cc: Venki Pallipadi <venkatesh.pallipadi@intel.com> Cc: Adam Belay <abelay@novell.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-02-05 06:30:08 +00:00
*/
#include <linux/plist.h>
pm qos infrastructure and interface The following patch is a generalization of the latency.c implementation done by Arjan last year. It provides infrastructure for more than one parameter, and exposes a user mode interface for processes to register pm_qos expectations of processes. This interface provides a kernel and user mode interface for registering performance expectations by drivers, subsystems and user space applications on one of the parameters. Currently we have {cpu_dma_latency, network_latency, network_throughput} as the initial set of pm_qos parameters. The infrastructure exposes multiple misc device nodes one per implemented parameter. The set of parameters implement is defined by pm_qos_power_init() and pm_qos_params.h. This is done because having the available parameters being runtime configurable or changeable from a driver was seen as too easy to abuse. For each parameter a list of performance requirements is maintained along with an aggregated target value. The aggregated target value is updated with changes to the requirement list or elements of the list. Typically the aggregated target value is simply the max or min of the requirement values held in the parameter list elements. >From kernel mode the use of this interface is simple: pm_qos_add_requirement(param_id, name, target_value): Will insert a named element in the list for that identified PM_QOS parameter with the target value. Upon change to this list the new target is recomputed and any registered notifiers are called only if the target value is now different. pm_qos_update_requirement(param_id, name, new_target_value): Will search the list identified by the param_id for the named list element and then update its target value, calling the notification tree if the aggregated target is changed. with that name is already registered. pm_qos_remove_requirement(param_id, name): Will search the identified list for the named element and remove it, after removal it will update the aggregate target and call the notification tree if the target was changed as a result of removing the named requirement. >From user mode: Only processes can register a pm_qos requirement. To provide for automatic cleanup for process the interface requires the process to register its parameter requirements in the following way: To register the default pm_qos target for the specific parameter, the process must open one of /dev/[cpu_dma_latency, network_latency, network_throughput] As long as the device node is held open that process has a registered requirement on the parameter. The name of the requirement is "process_<PID>" derived from the current->pid from within the open system call. To change the requested target value the process needs to write a s32 value to the open device node. This translates to a pm_qos_update_requirement call. To remove the user mode request for a target value simply close the device node. [akpm@linux-foundation.org: fix warnings] [akpm@linux-foundation.org: fix build] [akpm@linux-foundation.org: fix build again] [akpm@linux-foundation.org: coding-style fixes] Signed-off-by: mark gross <mgross@linux.intel.com> Cc: "John W. Linville" <linville@tuxdriver.com> Cc: Len Brown <lenb@kernel.org> Cc: Jaroslav Kysela <perex@suse.cz> Cc: Takashi Iwai <tiwai@suse.de> Cc: Arjan van de Ven <arjan@infradead.org> Cc: Venki Pallipadi <venkatesh.pallipadi@intel.com> Cc: Adam Belay <abelay@novell.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-02-05 06:30:08 +00:00
#include <linux/notifier.h>
#include <linux/miscdevice.h>
#include <linux/device.h>
#include <linux/workqueue.h>
pm qos infrastructure and interface The following patch is a generalization of the latency.c implementation done by Arjan last year. It provides infrastructure for more than one parameter, and exposes a user mode interface for processes to register pm_qos expectations of processes. This interface provides a kernel and user mode interface for registering performance expectations by drivers, subsystems and user space applications on one of the parameters. Currently we have {cpu_dma_latency, network_latency, network_throughput} as the initial set of pm_qos parameters. The infrastructure exposes multiple misc device nodes one per implemented parameter. The set of parameters implement is defined by pm_qos_power_init() and pm_qos_params.h. This is done because having the available parameters being runtime configurable or changeable from a driver was seen as too easy to abuse. For each parameter a list of performance requirements is maintained along with an aggregated target value. The aggregated target value is updated with changes to the requirement list or elements of the list. Typically the aggregated target value is simply the max or min of the requirement values held in the parameter list elements. >From kernel mode the use of this interface is simple: pm_qos_add_requirement(param_id, name, target_value): Will insert a named element in the list for that identified PM_QOS parameter with the target value. Upon change to this list the new target is recomputed and any registered notifiers are called only if the target value is now different. pm_qos_update_requirement(param_id, name, new_target_value): Will search the list identified by the param_id for the named list element and then update its target value, calling the notification tree if the aggregated target is changed. with that name is already registered. pm_qos_remove_requirement(param_id, name): Will search the identified list for the named element and remove it, after removal it will update the aggregate target and call the notification tree if the target was changed as a result of removing the named requirement. >From user mode: Only processes can register a pm_qos requirement. To provide for automatic cleanup for process the interface requires the process to register its parameter requirements in the following way: To register the default pm_qos target for the specific parameter, the process must open one of /dev/[cpu_dma_latency, network_latency, network_throughput] As long as the device node is held open that process has a registered requirement on the parameter. The name of the requirement is "process_<PID>" derived from the current->pid from within the open system call. To change the requested target value the process needs to write a s32 value to the open device node. This translates to a pm_qos_update_requirement call. To remove the user mode request for a target value simply close the device node. [akpm@linux-foundation.org: fix warnings] [akpm@linux-foundation.org: fix build] [akpm@linux-foundation.org: fix build again] [akpm@linux-foundation.org: coding-style fixes] Signed-off-by: mark gross <mgross@linux.intel.com> Cc: "John W. Linville" <linville@tuxdriver.com> Cc: Len Brown <lenb@kernel.org> Cc: Jaroslav Kysela <perex@suse.cz> Cc: Takashi Iwai <tiwai@suse.de> Cc: Arjan van de Ven <arjan@infradead.org> Cc: Venki Pallipadi <venkatesh.pallipadi@intel.com> Cc: Adam Belay <abelay@novell.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-02-05 06:30:08 +00:00
enum {
PM_QOS_RESERVED = 0,
PM_QOS_CPU_DMA_LATENCY,
PM_QOS_NETWORK_LATENCY,
PM_QOS_NETWORK_THROUGHPUT,
PM_QOS_MEMORY_BANDWIDTH,
/* insert new class ID */
PM_QOS_NUM_CLASSES,
};
pm qos infrastructure and interface The following patch is a generalization of the latency.c implementation done by Arjan last year. It provides infrastructure for more than one parameter, and exposes a user mode interface for processes to register pm_qos expectations of processes. This interface provides a kernel and user mode interface for registering performance expectations by drivers, subsystems and user space applications on one of the parameters. Currently we have {cpu_dma_latency, network_latency, network_throughput} as the initial set of pm_qos parameters. The infrastructure exposes multiple misc device nodes one per implemented parameter. The set of parameters implement is defined by pm_qos_power_init() and pm_qos_params.h. This is done because having the available parameters being runtime configurable or changeable from a driver was seen as too easy to abuse. For each parameter a list of performance requirements is maintained along with an aggregated target value. The aggregated target value is updated with changes to the requirement list or elements of the list. Typically the aggregated target value is simply the max or min of the requirement values held in the parameter list elements. >From kernel mode the use of this interface is simple: pm_qos_add_requirement(param_id, name, target_value): Will insert a named element in the list for that identified PM_QOS parameter with the target value. Upon change to this list the new target is recomputed and any registered notifiers are called only if the target value is now different. pm_qos_update_requirement(param_id, name, new_target_value): Will search the list identified by the param_id for the named list element and then update its target value, calling the notification tree if the aggregated target is changed. with that name is already registered. pm_qos_remove_requirement(param_id, name): Will search the identified list for the named element and remove it, after removal it will update the aggregate target and call the notification tree if the target was changed as a result of removing the named requirement. >From user mode: Only processes can register a pm_qos requirement. To provide for automatic cleanup for process the interface requires the process to register its parameter requirements in the following way: To register the default pm_qos target for the specific parameter, the process must open one of /dev/[cpu_dma_latency, network_latency, network_throughput] As long as the device node is held open that process has a registered requirement on the parameter. The name of the requirement is "process_<PID>" derived from the current->pid from within the open system call. To change the requested target value the process needs to write a s32 value to the open device node. This translates to a pm_qos_update_requirement call. To remove the user mode request for a target value simply close the device node. [akpm@linux-foundation.org: fix warnings] [akpm@linux-foundation.org: fix build] [akpm@linux-foundation.org: fix build again] [akpm@linux-foundation.org: coding-style fixes] Signed-off-by: mark gross <mgross@linux.intel.com> Cc: "John W. Linville" <linville@tuxdriver.com> Cc: Len Brown <lenb@kernel.org> Cc: Jaroslav Kysela <perex@suse.cz> Cc: Takashi Iwai <tiwai@suse.de> Cc: Arjan van de Ven <arjan@infradead.org> Cc: Venki Pallipadi <venkatesh.pallipadi@intel.com> Cc: Adam Belay <abelay@novell.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-02-05 06:30:08 +00:00
enum pm_qos_flags_status {
PM_QOS_FLAGS_UNDEFINED = -1,
PM_QOS_FLAGS_NONE,
PM_QOS_FLAGS_SOME,
PM_QOS_FLAGS_ALL,
};
pm qos infrastructure and interface The following patch is a generalization of the latency.c implementation done by Arjan last year. It provides infrastructure for more than one parameter, and exposes a user mode interface for processes to register pm_qos expectations of processes. This interface provides a kernel and user mode interface for registering performance expectations by drivers, subsystems and user space applications on one of the parameters. Currently we have {cpu_dma_latency, network_latency, network_throughput} as the initial set of pm_qos parameters. The infrastructure exposes multiple misc device nodes one per implemented parameter. The set of parameters implement is defined by pm_qos_power_init() and pm_qos_params.h. This is done because having the available parameters being runtime configurable or changeable from a driver was seen as too easy to abuse. For each parameter a list of performance requirements is maintained along with an aggregated target value. The aggregated target value is updated with changes to the requirement list or elements of the list. Typically the aggregated target value is simply the max or min of the requirement values held in the parameter list elements. >From kernel mode the use of this interface is simple: pm_qos_add_requirement(param_id, name, target_value): Will insert a named element in the list for that identified PM_QOS parameter with the target value. Upon change to this list the new target is recomputed and any registered notifiers are called only if the target value is now different. pm_qos_update_requirement(param_id, name, new_target_value): Will search the list identified by the param_id for the named list element and then update its target value, calling the notification tree if the aggregated target is changed. with that name is already registered. pm_qos_remove_requirement(param_id, name): Will search the identified list for the named element and remove it, after removal it will update the aggregate target and call the notification tree if the target was changed as a result of removing the named requirement. >From user mode: Only processes can register a pm_qos requirement. To provide for automatic cleanup for process the interface requires the process to register its parameter requirements in the following way: To register the default pm_qos target for the specific parameter, the process must open one of /dev/[cpu_dma_latency, network_latency, network_throughput] As long as the device node is held open that process has a registered requirement on the parameter. The name of the requirement is "process_<PID>" derived from the current->pid from within the open system call. To change the requested target value the process needs to write a s32 value to the open device node. This translates to a pm_qos_update_requirement call. To remove the user mode request for a target value simply close the device node. [akpm@linux-foundation.org: fix warnings] [akpm@linux-foundation.org: fix build] [akpm@linux-foundation.org: fix build again] [akpm@linux-foundation.org: coding-style fixes] Signed-off-by: mark gross <mgross@linux.intel.com> Cc: "John W. Linville" <linville@tuxdriver.com> Cc: Len Brown <lenb@kernel.org> Cc: Jaroslav Kysela <perex@suse.cz> Cc: Takashi Iwai <tiwai@suse.de> Cc: Arjan van de Ven <arjan@infradead.org> Cc: Venki Pallipadi <venkatesh.pallipadi@intel.com> Cc: Adam Belay <abelay@novell.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-02-05 06:30:08 +00:00
#define PM_QOS_DEFAULT_VALUE -1
idle governor: Avoid lock acquisition to read pm_qos before entering idle Thanks to the reviews and comments by Rafael, James, Mark and Andi. Here's version 2 of the patch incorporating your comments and also some update to my previous patch comments. I noticed that before entering idle state, the menu idle governor will look up the current pm_qos target value according to the list of qos requests received. This look up currently needs the acquisition of a lock to access the list of qos requests to find the qos target value, slowing down the entrance into idle state due to contention by multiple cpus to access this list. The contention is severe when there are a lot of cpus waking and going into idle. For example, for a simple workload that has 32 pair of processes ping ponging messages to each other, where 64 cpu cores are active in test system, I see the following profile with 37.82% of cpu cycles spent in contention of pm_qos_lock: - 37.82% swapper [kernel.kallsyms] [k] _raw_spin_lock_irqsave - _raw_spin_lock_irqsave - 95.65% pm_qos_request menu_select cpuidle_idle_call - cpu_idle 99.98% start_secondary A better approach will be to cache the updated pm_qos target value so reading it does not require lock acquisition as in the patch below. With this patch the contention for pm_qos_lock is removed and I saw a 2.2X increase in throughput for my message passing workload. cc: stable@kernel.org Signed-off-by: Tim Chen <tim.c.chen@linux.intel.com> Acked-by: Andi Kleen <ak@linux.intel.com> Acked-by: James Bottomley <James.Bottomley@suse.de> Acked-by: mark gross <markgross@thegnar.org> Signed-off-by: Len Brown <len.brown@intel.com>
2011-02-11 20:49:04 +00:00
#define PM_QOS_CPU_DMA_LAT_DEFAULT_VALUE (2000 * USEC_PER_SEC)
#define PM_QOS_NETWORK_LAT_DEFAULT_VALUE (2000 * USEC_PER_SEC)
#define PM_QOS_NETWORK_THROUGHPUT_DEFAULT_VALUE 0
#define PM_QOS_MEMORY_BANDWIDTH_DEFAULT_VALUE 0
#define PM_QOS_RESUME_LATENCY_DEFAULT_VALUE 0
PM / QoS: Introcuce latency tolerance device PM QoS type Add a new latency tolerance device PM QoS type to be use for specifying active state (RPM_ACTIVE) memory access (DMA) latency tolerance requirements for devices. It may be used to prevent hardware from choosing overly aggressive energy-saving operation modes (causing too much latency to appear) for the whole platform. This feature reqiures hardware support, so it only will be available for devices having a new .set_latency_tolerance() callback in struct dev_pm_info populated, in which case the routine pointed to by it should implement whatever is necessary to transfer the effective requirement value to the hardware. Whenever the effective latency tolerance changes for the device, its .set_latency_tolerance() callback will be executed and the effective value will be passed to it. If that value is negative, which means that the list of latency tolerance requirements for the device is empty, the callback is expected to switch the underlying hardware latency tolerance control mechanism to an autonomous mode if available. If that value is PM_QOS_LATENCY_ANY, in turn, and the hardware supports a special "no requirement" setting, the callback is expected to use it. That allows software to prevent the hardware from automatically updating the device's latency tolerance in response to its power state changes (e.g. during transitions from D3cold to D0), which generally may be done in the autonomous latency tolerance control mode. If .set_latency_tolerance() is present for the device, a new pm_qos_latency_tolerance_us attribute will be present in the devivce's power directory in sysfs. Then, user space can use that attribute to specify its latency tolerance requirement for the device, if any. Writing "any" to it means "no requirement, but do not let the hardware control latency tolerance" and writing "auto" to it allows the hardware to be switched to the autonomous mode if there are no other requirements from the kernel side in the device's list. This changeset includes a fix from Mika Westerberg. Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2014-02-10 23:35:38 +00:00
#define PM_QOS_LATENCY_TOLERANCE_DEFAULT_VALUE 0
#define PM_QOS_LATENCY_TOLERANCE_NO_CONSTRAINT (-1)
#define PM_QOS_LATENCY_ANY ((s32)(~(__u32)0 >> 1))
idle governor: Avoid lock acquisition to read pm_qos before entering idle Thanks to the reviews and comments by Rafael, James, Mark and Andi. Here's version 2 of the patch incorporating your comments and also some update to my previous patch comments. I noticed that before entering idle state, the menu idle governor will look up the current pm_qos target value according to the list of qos requests received. This look up currently needs the acquisition of a lock to access the list of qos requests to find the qos target value, slowing down the entrance into idle state due to contention by multiple cpus to access this list. The contention is severe when there are a lot of cpus waking and going into idle. For example, for a simple workload that has 32 pair of processes ping ponging messages to each other, where 64 cpu cores are active in test system, I see the following profile with 37.82% of cpu cycles spent in contention of pm_qos_lock: - 37.82% swapper [kernel.kallsyms] [k] _raw_spin_lock_irqsave - _raw_spin_lock_irqsave - 95.65% pm_qos_request menu_select cpuidle_idle_call - cpu_idle 99.98% start_secondary A better approach will be to cache the updated pm_qos target value so reading it does not require lock acquisition as in the patch below. With this patch the contention for pm_qos_lock is removed and I saw a 2.2X increase in throughput for my message passing workload. cc: stable@kernel.org Signed-off-by: Tim Chen <tim.c.chen@linux.intel.com> Acked-by: Andi Kleen <ak@linux.intel.com> Acked-by: James Bottomley <James.Bottomley@suse.de> Acked-by: mark gross <markgross@thegnar.org> Signed-off-by: Len Brown <len.brown@intel.com>
2011-02-11 20:49:04 +00:00
#define PM_QOS_FLAG_NO_POWER_OFF (1 << 0)
#define PM_QOS_FLAG_REMOTE_WAKEUP (1 << 1)
struct pm_qos_request {
struct plist_node node;
int pm_qos_class;
struct delayed_work work; /* for pm_qos_update_request_timeout */
};
pm qos infrastructure and interface The following patch is a generalization of the latency.c implementation done by Arjan last year. It provides infrastructure for more than one parameter, and exposes a user mode interface for processes to register pm_qos expectations of processes. This interface provides a kernel and user mode interface for registering performance expectations by drivers, subsystems and user space applications on one of the parameters. Currently we have {cpu_dma_latency, network_latency, network_throughput} as the initial set of pm_qos parameters. The infrastructure exposes multiple misc device nodes one per implemented parameter. The set of parameters implement is defined by pm_qos_power_init() and pm_qos_params.h. This is done because having the available parameters being runtime configurable or changeable from a driver was seen as too easy to abuse. For each parameter a list of performance requirements is maintained along with an aggregated target value. The aggregated target value is updated with changes to the requirement list or elements of the list. Typically the aggregated target value is simply the max or min of the requirement values held in the parameter list elements. >From kernel mode the use of this interface is simple: pm_qos_add_requirement(param_id, name, target_value): Will insert a named element in the list for that identified PM_QOS parameter with the target value. Upon change to this list the new target is recomputed and any registered notifiers are called only if the target value is now different. pm_qos_update_requirement(param_id, name, new_target_value): Will search the list identified by the param_id for the named list element and then update its target value, calling the notification tree if the aggregated target is changed. with that name is already registered. pm_qos_remove_requirement(param_id, name): Will search the identified list for the named element and remove it, after removal it will update the aggregate target and call the notification tree if the target was changed as a result of removing the named requirement. >From user mode: Only processes can register a pm_qos requirement. To provide for automatic cleanup for process the interface requires the process to register its parameter requirements in the following way: To register the default pm_qos target for the specific parameter, the process must open one of /dev/[cpu_dma_latency, network_latency, network_throughput] As long as the device node is held open that process has a registered requirement on the parameter. The name of the requirement is "process_<PID>" derived from the current->pid from within the open system call. To change the requested target value the process needs to write a s32 value to the open device node. This translates to a pm_qos_update_requirement call. To remove the user mode request for a target value simply close the device node. [akpm@linux-foundation.org: fix warnings] [akpm@linux-foundation.org: fix build] [akpm@linux-foundation.org: fix build again] [akpm@linux-foundation.org: coding-style fixes] Signed-off-by: mark gross <mgross@linux.intel.com> Cc: "John W. Linville" <linville@tuxdriver.com> Cc: Len Brown <lenb@kernel.org> Cc: Jaroslav Kysela <perex@suse.cz> Cc: Takashi Iwai <tiwai@suse.de> Cc: Arjan van de Ven <arjan@infradead.org> Cc: Venki Pallipadi <venkatesh.pallipadi@intel.com> Cc: Adam Belay <abelay@novell.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-02-05 06:30:08 +00:00
struct pm_qos_flags_request {
struct list_head node;
s32 flags; /* Do not change to 64 bit */
};
enum dev_pm_qos_req_type {
DEV_PM_QOS_RESUME_LATENCY = 1,
PM / QoS: Introcuce latency tolerance device PM QoS type Add a new latency tolerance device PM QoS type to be use for specifying active state (RPM_ACTIVE) memory access (DMA) latency tolerance requirements for devices. It may be used to prevent hardware from choosing overly aggressive energy-saving operation modes (causing too much latency to appear) for the whole platform. This feature reqiures hardware support, so it only will be available for devices having a new .set_latency_tolerance() callback in struct dev_pm_info populated, in which case the routine pointed to by it should implement whatever is necessary to transfer the effective requirement value to the hardware. Whenever the effective latency tolerance changes for the device, its .set_latency_tolerance() callback will be executed and the effective value will be passed to it. If that value is negative, which means that the list of latency tolerance requirements for the device is empty, the callback is expected to switch the underlying hardware latency tolerance control mechanism to an autonomous mode if available. If that value is PM_QOS_LATENCY_ANY, in turn, and the hardware supports a special "no requirement" setting, the callback is expected to use it. That allows software to prevent the hardware from automatically updating the device's latency tolerance in response to its power state changes (e.g. during transitions from D3cold to D0), which generally may be done in the autonomous latency tolerance control mode. If .set_latency_tolerance() is present for the device, a new pm_qos_latency_tolerance_us attribute will be present in the devivce's power directory in sysfs. Then, user space can use that attribute to specify its latency tolerance requirement for the device, if any. Writing "any" to it means "no requirement, but do not let the hardware control latency tolerance" and writing "auto" to it allows the hardware to be switched to the autonomous mode if there are no other requirements from the kernel side in the device's list. This changeset includes a fix from Mika Westerberg. Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2014-02-10 23:35:38 +00:00
DEV_PM_QOS_LATENCY_TOLERANCE,
DEV_PM_QOS_FLAGS,
};
struct dev_pm_qos_request {
enum dev_pm_qos_req_type type;
union {
struct plist_node pnode;
struct pm_qos_flags_request flr;
} data;
struct device *dev;
};
enum pm_qos_type {
PM_QOS_UNITIALIZED,
PM_QOS_MAX, /* return the largest value */
PM_QOS_MIN, /* return the smallest value */
PM_QOS_SUM /* return the sum */
};
/*
* Note: The lockless read path depends on the CPU accessing target_value
* or effective_flags atomically. Atomic access is only guaranteed on all CPU
* types linux supports for 32 bit quantites
*/
struct pm_qos_constraints {
struct plist_head list;
s32 target_value; /* Do not change to 64 bit */
s32 default_value;
s32 no_constraint_value;
enum pm_qos_type type;
struct blocking_notifier_head *notifiers;
};
struct pm_qos_flags {
struct list_head list;
s32 effective_flags; /* Do not change to 64 bit */
};
struct dev_pm_qos {
struct pm_qos_constraints resume_latency;
PM / QoS: Introcuce latency tolerance device PM QoS type Add a new latency tolerance device PM QoS type to be use for specifying active state (RPM_ACTIVE) memory access (DMA) latency tolerance requirements for devices. It may be used to prevent hardware from choosing overly aggressive energy-saving operation modes (causing too much latency to appear) for the whole platform. This feature reqiures hardware support, so it only will be available for devices having a new .set_latency_tolerance() callback in struct dev_pm_info populated, in which case the routine pointed to by it should implement whatever is necessary to transfer the effective requirement value to the hardware. Whenever the effective latency tolerance changes for the device, its .set_latency_tolerance() callback will be executed and the effective value will be passed to it. If that value is negative, which means that the list of latency tolerance requirements for the device is empty, the callback is expected to switch the underlying hardware latency tolerance control mechanism to an autonomous mode if available. If that value is PM_QOS_LATENCY_ANY, in turn, and the hardware supports a special "no requirement" setting, the callback is expected to use it. That allows software to prevent the hardware from automatically updating the device's latency tolerance in response to its power state changes (e.g. during transitions from D3cold to D0), which generally may be done in the autonomous latency tolerance control mode. If .set_latency_tolerance() is present for the device, a new pm_qos_latency_tolerance_us attribute will be present in the devivce's power directory in sysfs. Then, user space can use that attribute to specify its latency tolerance requirement for the device, if any. Writing "any" to it means "no requirement, but do not let the hardware control latency tolerance" and writing "auto" to it allows the hardware to be switched to the autonomous mode if there are no other requirements from the kernel side in the device's list. This changeset includes a fix from Mika Westerberg. Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2014-02-10 23:35:38 +00:00
struct pm_qos_constraints latency_tolerance;
struct pm_qos_flags flags;
struct dev_pm_qos_request *resume_latency_req;
PM / QoS: Introcuce latency tolerance device PM QoS type Add a new latency tolerance device PM QoS type to be use for specifying active state (RPM_ACTIVE) memory access (DMA) latency tolerance requirements for devices. It may be used to prevent hardware from choosing overly aggressive energy-saving operation modes (causing too much latency to appear) for the whole platform. This feature reqiures hardware support, so it only will be available for devices having a new .set_latency_tolerance() callback in struct dev_pm_info populated, in which case the routine pointed to by it should implement whatever is necessary to transfer the effective requirement value to the hardware. Whenever the effective latency tolerance changes for the device, its .set_latency_tolerance() callback will be executed and the effective value will be passed to it. If that value is negative, which means that the list of latency tolerance requirements for the device is empty, the callback is expected to switch the underlying hardware latency tolerance control mechanism to an autonomous mode if available. If that value is PM_QOS_LATENCY_ANY, in turn, and the hardware supports a special "no requirement" setting, the callback is expected to use it. That allows software to prevent the hardware from automatically updating the device's latency tolerance in response to its power state changes (e.g. during transitions from D3cold to D0), which generally may be done in the autonomous latency tolerance control mode. If .set_latency_tolerance() is present for the device, a new pm_qos_latency_tolerance_us attribute will be present in the devivce's power directory in sysfs. Then, user space can use that attribute to specify its latency tolerance requirement for the device, if any. Writing "any" to it means "no requirement, but do not let the hardware control latency tolerance" and writing "auto" to it allows the hardware to be switched to the autonomous mode if there are no other requirements from the kernel side in the device's list. This changeset includes a fix from Mika Westerberg. Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2014-02-10 23:35:38 +00:00
struct dev_pm_qos_request *latency_tolerance_req;
struct dev_pm_qos_request *flags_req;
};
/* Action requested to pm_qos_update_target */
enum pm_qos_req_action {
PM_QOS_ADD_REQ, /* Add a new request */
PM_QOS_UPDATE_REQ, /* Update an existing request */
PM_QOS_REMOVE_REQ /* Remove an existing request */
};
static inline int dev_pm_qos_request_active(struct dev_pm_qos_request *req)
{
return req->dev != NULL;
}
int pm_qos_update_target(struct pm_qos_constraints *c, struct plist_node *node,
enum pm_qos_req_action action, int value);
bool pm_qos_update_flags(struct pm_qos_flags *pqf,
struct pm_qos_flags_request *req,
enum pm_qos_req_action action, s32 val);
void pm_qos_add_request(struct pm_qos_request *req, int pm_qos_class,
s32 value);
void pm_qos_update_request(struct pm_qos_request *req,
s32 new_value);
void pm_qos_update_request_timeout(struct pm_qos_request *req,
s32 new_value, unsigned long timeout_us);
void pm_qos_remove_request(struct pm_qos_request *req);
pm qos infrastructure and interface The following patch is a generalization of the latency.c implementation done by Arjan last year. It provides infrastructure for more than one parameter, and exposes a user mode interface for processes to register pm_qos expectations of processes. This interface provides a kernel and user mode interface for registering performance expectations by drivers, subsystems and user space applications on one of the parameters. Currently we have {cpu_dma_latency, network_latency, network_throughput} as the initial set of pm_qos parameters. The infrastructure exposes multiple misc device nodes one per implemented parameter. The set of parameters implement is defined by pm_qos_power_init() and pm_qos_params.h. This is done because having the available parameters being runtime configurable or changeable from a driver was seen as too easy to abuse. For each parameter a list of performance requirements is maintained along with an aggregated target value. The aggregated target value is updated with changes to the requirement list or elements of the list. Typically the aggregated target value is simply the max or min of the requirement values held in the parameter list elements. >From kernel mode the use of this interface is simple: pm_qos_add_requirement(param_id, name, target_value): Will insert a named element in the list for that identified PM_QOS parameter with the target value. Upon change to this list the new target is recomputed and any registered notifiers are called only if the target value is now different. pm_qos_update_requirement(param_id, name, new_target_value): Will search the list identified by the param_id for the named list element and then update its target value, calling the notification tree if the aggregated target is changed. with that name is already registered. pm_qos_remove_requirement(param_id, name): Will search the identified list for the named element and remove it, after removal it will update the aggregate target and call the notification tree if the target was changed as a result of removing the named requirement. >From user mode: Only processes can register a pm_qos requirement. To provide for automatic cleanup for process the interface requires the process to register its parameter requirements in the following way: To register the default pm_qos target for the specific parameter, the process must open one of /dev/[cpu_dma_latency, network_latency, network_throughput] As long as the device node is held open that process has a registered requirement on the parameter. The name of the requirement is "process_<PID>" derived from the current->pid from within the open system call. To change the requested target value the process needs to write a s32 value to the open device node. This translates to a pm_qos_update_requirement call. To remove the user mode request for a target value simply close the device node. [akpm@linux-foundation.org: fix warnings] [akpm@linux-foundation.org: fix build] [akpm@linux-foundation.org: fix build again] [akpm@linux-foundation.org: coding-style fixes] Signed-off-by: mark gross <mgross@linux.intel.com> Cc: "John W. Linville" <linville@tuxdriver.com> Cc: Len Brown <lenb@kernel.org> Cc: Jaroslav Kysela <perex@suse.cz> Cc: Takashi Iwai <tiwai@suse.de> Cc: Arjan van de Ven <arjan@infradead.org> Cc: Venki Pallipadi <venkatesh.pallipadi@intel.com> Cc: Adam Belay <abelay@novell.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-02-05 06:30:08 +00:00
int pm_qos_request(int pm_qos_class);
int pm_qos_add_notifier(int pm_qos_class, struct notifier_block *notifier);
int pm_qos_remove_notifier(int pm_qos_class, struct notifier_block *notifier);
int pm_qos_request_active(struct pm_qos_request *req);
s32 pm_qos_read_value(struct pm_qos_constraints *c);
#ifdef CONFIG_PM
enum pm_qos_flags_status __dev_pm_qos_flags(struct device *dev, s32 mask);
enum pm_qos_flags_status dev_pm_qos_flags(struct device *dev, s32 mask);
PM / Runtime: Use device PM QoS constraints (v2) Make the runtime PM core use device PM QoS constraints to check if it is allowed to suspend a given device, so that an error code is returned if the device's own PM QoS constraint is negative or one of its children has already been suspended for too long. If this is not the case, the maximum estimated time the device is allowed to be suspended, computed as the minimum of the device's PM QoS constraint and the PM QoS constraints of its children (reduced by the difference between the current time and their suspend times) is stored in a new device's PM field power.max_time_suspended_ns that can be used by the device's subsystem or PM domain to decide whether or not to put the device into lower-power (and presumably higher-latency) states later (if the constraint is 0, which means "no constraint", the power.max_time_suspended_ns is set to -1). Additionally, the time of execution of the subsystem-level .runtime_suspend() callback for the device is recorded in the new power.suspend_time field for later use by the device's subsystem or PM domain along with power.max_time_suspended_ns (it also is used by the core code when the device's parent is suspended). Introduce a new helper function, pm_runtime_update_max_time_suspended(), allowing subsystems and PM domains (or device drivers) to update the power.max_time_suspended_ns field, for example after changing the power state of a suspended device. Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
2011-11-30 23:01:31 +00:00
s32 __dev_pm_qos_read_value(struct device *dev);
s32 dev_pm_qos_read_value(struct device *dev);
int dev_pm_qos_add_request(struct device *dev, struct dev_pm_qos_request *req,
enum dev_pm_qos_req_type type, s32 value);
int dev_pm_qos_update_request(struct dev_pm_qos_request *req, s32 new_value);
int dev_pm_qos_remove_request(struct dev_pm_qos_request *req);
int dev_pm_qos_add_notifier(struct device *dev,
struct notifier_block *notifier);
int dev_pm_qos_remove_notifier(struct device *dev,
struct notifier_block *notifier);
int dev_pm_qos_add_global_notifier(struct notifier_block *notifier);
int dev_pm_qos_remove_global_notifier(struct notifier_block *notifier);
void dev_pm_qos_constraints_init(struct device *dev);
void dev_pm_qos_constraints_destroy(struct device *dev);
PM / QoS: Introduce dev_pm_qos_add_ancestor_request() Some devices, like the I2C controller on SH7372, are not necessary for providing power to their children or forwarding wakeup signals (and generally interrupts) from them. They are only needed by their children when there's some data to transfer, so they may be suspended for the majority of time and resumed on demand, when the children have data to send or receive. For this purpose, however, their power.ignore_children flags have to be set, or the PM core wouldn't allow them to be suspended while their children were active. Unfortunately, in some situations it may take too much time to resume such devices so that they can assist their children in transferring data. For example, if such a device belongs to a PM domain which goes to the "power off" state when that device is suspended, it may take too much time to restore power to the domain in response to the request from one of the device's children. In that case, if the parent's resume time is critical, the domain should stay in the "power on" state, although it still may be desirable to power manage the parent itself (e.g. by manipulating its clock). In general, device PM QoS may be used to address this problem. Namely, if the device's children added PM QoS latency constraints for it, they would be able to prevent it from being put into an overly deep low-power state. However, in some cases the devices needing to be serviced are not the immediate children of a "children-ignoring" device, but its grandchildren or even less direct descendants. In those cases, the entity wanting to add a PM QoS request for a given device's ancestor that ignores its children will have to find it in the first place, so introduce a new helper function that may be used to achieve that. This function, dev_pm_qos_add_ancestor_request(), will search for the first ancestor of the given device whose power.ignore_children flag is set and will add a device PM QoS latency request for that ancestor on behalf of the caller. The request added this way may be removed with the help of dev_pm_qos_remove_request() in the future, like any other device PM QoS latency request. Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
2011-12-23 00:23:52 +00:00
int dev_pm_qos_add_ancestor_request(struct device *dev,
struct dev_pm_qos_request *req,
enum dev_pm_qos_req_type type, s32 value);
int dev_pm_qos_expose_latency_limit(struct device *dev, s32 value);
void dev_pm_qos_hide_latency_limit(struct device *dev);
int dev_pm_qos_expose_flags(struct device *dev, s32 value);
void dev_pm_qos_hide_flags(struct device *dev);
int dev_pm_qos_update_flags(struct device *dev, s32 mask, bool set);
s32 dev_pm_qos_get_user_latency_tolerance(struct device *dev);
int dev_pm_qos_update_user_latency_tolerance(struct device *dev, s32 val);
int dev_pm_qos_expose_latency_tolerance(struct device *dev);
void dev_pm_qos_hide_latency_tolerance(struct device *dev);
static inline s32 dev_pm_qos_requested_resume_latency(struct device *dev)
{
return dev->power.qos->resume_latency_req->data.pnode.prio;
}
static inline s32 dev_pm_qos_requested_flags(struct device *dev)
{
return dev->power.qos->flags_req->data.flr.flags;
}
#else
static inline enum pm_qos_flags_status __dev_pm_qos_flags(struct device *dev,
s32 mask)
{ return PM_QOS_FLAGS_UNDEFINED; }
static inline enum pm_qos_flags_status dev_pm_qos_flags(struct device *dev,
s32 mask)
{ return PM_QOS_FLAGS_UNDEFINED; }
PM / Runtime: Use device PM QoS constraints (v2) Make the runtime PM core use device PM QoS constraints to check if it is allowed to suspend a given device, so that an error code is returned if the device's own PM QoS constraint is negative or one of its children has already been suspended for too long. If this is not the case, the maximum estimated time the device is allowed to be suspended, computed as the minimum of the device's PM QoS constraint and the PM QoS constraints of its children (reduced by the difference between the current time and their suspend times) is stored in a new device's PM field power.max_time_suspended_ns that can be used by the device's subsystem or PM domain to decide whether or not to put the device into lower-power (and presumably higher-latency) states later (if the constraint is 0, which means "no constraint", the power.max_time_suspended_ns is set to -1). Additionally, the time of execution of the subsystem-level .runtime_suspend() callback for the device is recorded in the new power.suspend_time field for later use by the device's subsystem or PM domain along with power.max_time_suspended_ns (it also is used by the core code when the device's parent is suspended). Introduce a new helper function, pm_runtime_update_max_time_suspended(), allowing subsystems and PM domains (or device drivers) to update the power.max_time_suspended_ns field, for example after changing the power state of a suspended device. Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
2011-11-30 23:01:31 +00:00
static inline s32 __dev_pm_qos_read_value(struct device *dev)
{ return 0; }
static inline s32 dev_pm_qos_read_value(struct device *dev)
{ return 0; }
static inline int dev_pm_qos_add_request(struct device *dev,
struct dev_pm_qos_request *req,
enum dev_pm_qos_req_type type,
s32 value)
{ return 0; }
static inline int dev_pm_qos_update_request(struct dev_pm_qos_request *req,
s32 new_value)
{ return 0; }
static inline int dev_pm_qos_remove_request(struct dev_pm_qos_request *req)
{ return 0; }
static inline int dev_pm_qos_add_notifier(struct device *dev,
struct notifier_block *notifier)
{ return 0; }
static inline int dev_pm_qos_remove_notifier(struct device *dev,
struct notifier_block *notifier)
{ return 0; }
static inline int dev_pm_qos_add_global_notifier(
struct notifier_block *notifier)
{ return 0; }
static inline int dev_pm_qos_remove_global_notifier(
struct notifier_block *notifier)
{ return 0; }
static inline void dev_pm_qos_constraints_init(struct device *dev)
{
dev->power.power_state = PMSG_ON;
}
static inline void dev_pm_qos_constraints_destroy(struct device *dev)
{
dev->power.power_state = PMSG_INVALID;
}
PM / QoS: Introduce dev_pm_qos_add_ancestor_request() Some devices, like the I2C controller on SH7372, are not necessary for providing power to their children or forwarding wakeup signals (and generally interrupts) from them. They are only needed by their children when there's some data to transfer, so they may be suspended for the majority of time and resumed on demand, when the children have data to send or receive. For this purpose, however, their power.ignore_children flags have to be set, or the PM core wouldn't allow them to be suspended while their children were active. Unfortunately, in some situations it may take too much time to resume such devices so that they can assist their children in transferring data. For example, if such a device belongs to a PM domain which goes to the "power off" state when that device is suspended, it may take too much time to restore power to the domain in response to the request from one of the device's children. In that case, if the parent's resume time is critical, the domain should stay in the "power on" state, although it still may be desirable to power manage the parent itself (e.g. by manipulating its clock). In general, device PM QoS may be used to address this problem. Namely, if the device's children added PM QoS latency constraints for it, they would be able to prevent it from being put into an overly deep low-power state. However, in some cases the devices needing to be serviced are not the immediate children of a "children-ignoring" device, but its grandchildren or even less direct descendants. In those cases, the entity wanting to add a PM QoS request for a given device's ancestor that ignores its children will have to find it in the first place, so introduce a new helper function that may be used to achieve that. This function, dev_pm_qos_add_ancestor_request(), will search for the first ancestor of the given device whose power.ignore_children flag is set and will add a device PM QoS latency request for that ancestor on behalf of the caller. The request added this way may be removed with the help of dev_pm_qos_remove_request() in the future, like any other device PM QoS latency request. Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
2011-12-23 00:23:52 +00:00
static inline int dev_pm_qos_add_ancestor_request(struct device *dev,
struct dev_pm_qos_request *req,
enum dev_pm_qos_req_type type,
s32 value)
PM / QoS: Introduce dev_pm_qos_add_ancestor_request() Some devices, like the I2C controller on SH7372, are not necessary for providing power to their children or forwarding wakeup signals (and generally interrupts) from them. They are only needed by their children when there's some data to transfer, so they may be suspended for the majority of time and resumed on demand, when the children have data to send or receive. For this purpose, however, their power.ignore_children flags have to be set, or the PM core wouldn't allow them to be suspended while their children were active. Unfortunately, in some situations it may take too much time to resume such devices so that they can assist their children in transferring data. For example, if such a device belongs to a PM domain which goes to the "power off" state when that device is suspended, it may take too much time to restore power to the domain in response to the request from one of the device's children. In that case, if the parent's resume time is critical, the domain should stay in the "power on" state, although it still may be desirable to power manage the parent itself (e.g. by manipulating its clock). In general, device PM QoS may be used to address this problem. Namely, if the device's children added PM QoS latency constraints for it, they would be able to prevent it from being put into an overly deep low-power state. However, in some cases the devices needing to be serviced are not the immediate children of a "children-ignoring" device, but its grandchildren or even less direct descendants. In those cases, the entity wanting to add a PM QoS request for a given device's ancestor that ignores its children will have to find it in the first place, so introduce a new helper function that may be used to achieve that. This function, dev_pm_qos_add_ancestor_request(), will search for the first ancestor of the given device whose power.ignore_children flag is set and will add a device PM QoS latency request for that ancestor on behalf of the caller. The request added this way may be removed with the help of dev_pm_qos_remove_request() in the future, like any other device PM QoS latency request. Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
2011-12-23 00:23:52 +00:00
{ return 0; }
static inline int dev_pm_qos_expose_latency_limit(struct device *dev, s32 value)
{ return 0; }
static inline void dev_pm_qos_hide_latency_limit(struct device *dev) {}
static inline int dev_pm_qos_expose_flags(struct device *dev, s32 value)
{ return 0; }
static inline void dev_pm_qos_hide_flags(struct device *dev) {}
static inline int dev_pm_qos_update_flags(struct device *dev, s32 m, bool set)
{ return 0; }
PM / QoS: Introcuce latency tolerance device PM QoS type Add a new latency tolerance device PM QoS type to be use for specifying active state (RPM_ACTIVE) memory access (DMA) latency tolerance requirements for devices. It may be used to prevent hardware from choosing overly aggressive energy-saving operation modes (causing too much latency to appear) for the whole platform. This feature reqiures hardware support, so it only will be available for devices having a new .set_latency_tolerance() callback in struct dev_pm_info populated, in which case the routine pointed to by it should implement whatever is necessary to transfer the effective requirement value to the hardware. Whenever the effective latency tolerance changes for the device, its .set_latency_tolerance() callback will be executed and the effective value will be passed to it. If that value is negative, which means that the list of latency tolerance requirements for the device is empty, the callback is expected to switch the underlying hardware latency tolerance control mechanism to an autonomous mode if available. If that value is PM_QOS_LATENCY_ANY, in turn, and the hardware supports a special "no requirement" setting, the callback is expected to use it. That allows software to prevent the hardware from automatically updating the device's latency tolerance in response to its power state changes (e.g. during transitions from D3cold to D0), which generally may be done in the autonomous latency tolerance control mode. If .set_latency_tolerance() is present for the device, a new pm_qos_latency_tolerance_us attribute will be present in the devivce's power directory in sysfs. Then, user space can use that attribute to specify its latency tolerance requirement for the device, if any. Writing "any" to it means "no requirement, but do not let the hardware control latency tolerance" and writing "auto" to it allows the hardware to be switched to the autonomous mode if there are no other requirements from the kernel side in the device's list. This changeset includes a fix from Mika Westerberg. Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2014-02-10 23:35:38 +00:00
static inline s32 dev_pm_qos_get_user_latency_tolerance(struct device *dev)
{ return PM_QOS_LATENCY_TOLERANCE_NO_CONSTRAINT; }
static inline int dev_pm_qos_update_user_latency_tolerance(struct device *dev, s32 val)
{ return 0; }
static inline int dev_pm_qos_expose_latency_tolerance(struct device *dev)
{ return 0; }
static inline void dev_pm_qos_hide_latency_tolerance(struct device *dev) {}
static inline s32 dev_pm_qos_requested_resume_latency(struct device *dev) { return 0; }
static inline s32 dev_pm_qos_requested_flags(struct device *dev) { return 0; }
#endif
#endif