summaryrefslogtreecommitdiff
path: root/Documentation/power/pm_qos_interface.txt
AgeCommit message (Collapse)AuthorFilesLines
2014-09-25PM / QoS: Add PM_QOS_MEMORY_BANDWIDTH classTomeu Vizoso1-1/+3
Also adds a class type PM_QOS_SUM that aggregates the values by summing them. It can be used by memory controllers to calculate the optimum clock frequency based on the bandwidth needs of the different memory clients. Signed-off-by: Tomeu Vizoso <tomeu.vizoso@collabora.com> Acked-by: Pavel Machek <pavel@ucw.cz> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2014-02-11PM / QoS: Add type to dev_pm_qos_add_ancestor_request() argumentsRafael J. Wysocki1-2/+4
Rework dev_pm_qos_add_ancestor_request() so that device PM QoS type is passed to it as the third argument and make it support the DEV_PM_QOS_LATENCY_TOLERANCE device PM QoS type (in addition to DEV_PM_QOS_RESUME_LATENCY). That will allow the drivers of devices without latency tolerance hardware support to use their ancestors having it as proxies for their latency tolerance requirements. Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2014-02-11PM / QoS: Introcuce latency tolerance device PM QoS typeRafael J. Wysocki1-9/+50
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>
2014-02-11PM / QoS: Rename device resume latency QoS itemsRafael J. Wysocki1-21/+16
Rename symbols, variables, functions and structure fields related do the resume latency device PM QoS type so that it is clear where they belong (in particular, to avoid confusion with the latency tolerance device PM QoS type introduced by a subsequent changeset). Update the PM QoS documentation to better reflect its current state. Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2013-06-23PM / QoS: Update Documentation/power/pm_qos_interface.txtlan,Tianyu1-7/+43
Update PM QoS documentation after recent changes. [rjw: Changelog] Signed-off-by: Lan Tianyu <tianyu.lan@intel.com> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2012-10-23PM / QoS: Introduce PM QoS device flags supportRafael J. Wysocki1-1/+1
Modify the device PM QoS core code to support PM QoS flags requests. First, add a new field of type struct pm_qos_flags called "flags" to struct dev_pm_qos for representing the list of PM QoS flags requests for the given device. Accordingly, add a new "type" field to struct dev_pm_qos_request (along with an enum for representing request types) and a new member called "flr" to its data union for representig flags requests. Second, modify dev_pm_qos_add_request(), dev_pm_qos_update_request(), the internal routine apply_constraint() used by them and their existing callers to cover flags requests as well as latency requests. In particular, dev_pm_qos_add_request() gets a new argument called "type" for specifying the type of a request to be added. Finally, introduce two routines, __dev_pm_qos_flags() and dev_pm_qos_flags(), allowing their callers to check which PM QoS flags have been requested for the given device (the caller is supposed to pass the mask of flags to check as the routine's second argument and examine its return value for the result). Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> Reviewed-by: Jean Pihet <j-pihet@ti.com> Reviewed-by: mark gross <markgross@thegnar.org>
2011-10-04PM / QoS: Update Documentation for the pm_qos and dev_pm_qos frameworksJean Pihet1-5/+87
Update the documentation for the recently updated pm_qos API, kernel and user space. Add documentation for the per-device PM QoS (dev_pm_qos) framework API. Signed-off-by: Jean Pihet <j-pihet@ti.com> Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
2010-05-11PM QOS updateMark Gross1-23/+25
This patch changes the string based list management to a handle base implementation to help with the hot path use of pm-qos, it also renames much of the API to use "request" as opposed to "requirement" that was used in the initial implementation. I did this because request more accurately represents what it actually does. Also, I added a string based ABI for users wanting to use a string interface. So if the user writes 0xDDDDDDDD formatted hex it will be accepted by the interface. (someone asked me for it and I don't think it hurts anything.) This patch updates some documentation input I got from Randy. Signed-off-by: markgross <mgross@linux.intel.com> Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
2008-08-06pm_qos: spelling fixesRichard Hughes1-1/+6
A documentation cleanup patch. With a minor tweak to clarify units for kbs. [akpm@linux-foundation.org: coding-style fixes] Signed-off-by: mark gross <mgross@linux.intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-03-13documentation: Move power-related files to Documentation/power/Randy Dunlap1-0/+59
Move 00-INDEX entries to power/00-INDEX (and add entry for pm_qos_interface.txt). Update references to moved filenames. Fix some trailing whitespace. Signed-off-by: Randy Dunlap <randy.dunlap@oracle.com> Signed-off-by: Len Brown <len.brown@intel.com>