diff options
Diffstat (limited to 'Documentation/power')
| -rw-r--r-- | Documentation/power/devices.txt | 16 | ||||
| -rw-r--r-- | Documentation/power/notifiers.txt | 53 | ||||
| -rw-r--r-- | Documentation/power/opp.txt | 2 | ||||
| -rw-r--r-- | Documentation/power/swsusp.txt | 4 | ||||
| -rw-r--r-- | Documentation/power/userland-swsusp.txt | 6 |
5 files changed, 40 insertions, 41 deletions
diff --git a/Documentation/power/devices.txt b/Documentation/power/devices.txt index f023ba6bba62..88880839ece4 100644 --- a/Documentation/power/devices.txt +++ b/Documentation/power/devices.txt @@ -279,11 +279,15 @@ When the system goes into the standby or memory sleep state, the phases are: time.) Unlike the other suspend-related phases, during the prepare phase the device tree is traversed top-down. - The prepare phase uses only a bus callback. After the callback method - returns, no new children may be registered below the device. The method - may also prepare the device or driver in some way for the upcoming - system power transition, but it should not put the device into a - low-power state. + In addition to that, if device drivers need to allocate additional + memory to be able to hadle device suspend correctly, that should be + done in the prepare phase. + + After the prepare callback method returns, no new children may be + registered below the device. The method may also prepare the device or + driver in some way for the upcoming system power transition (for + example, by allocating additional memory required for this purpose), but + it should not put the device into a low-power state. 2. The suspend methods should quiesce the device to stop it from performing I/O. They also may save the device registers and put it into the @@ -367,7 +371,7 @@ Drivers need to be able to handle hardware which has been reset since the suspend methods were called, for example by complete reinitialization. This may be the hardest part, and the one most protected by NDA'd documents and chip errata. It's simplest if the hardware state hasn't changed since -the suspend was carried out, but that can't be guaranteed (in fact, it ususally +the suspend was carried out, but that can't be guaranteed (in fact, it usually is not the case). Drivers must also be prepared to notice that the device has been removed diff --git a/Documentation/power/notifiers.txt b/Documentation/power/notifiers.txt index ae1b7ec07684..c2a4a346c0d9 100644 --- a/Documentation/power/notifiers.txt +++ b/Documentation/power/notifiers.txt @@ -1,46 +1,41 @@ Suspend notifiers - (C) 2007 Rafael J. Wysocki <rjw@sisk.pl>, GPL - -There are some operations that device drivers may want to carry out in their -.suspend() routines, but shouldn't, because they can cause the hibernation or -suspend to fail. For example, a driver may want to allocate a substantial amount -of memory (like 50 MB) in .suspend(), but that shouldn't be done after the -swsusp's memory shrinker has run. - -Also, there may be some operations, that subsystems want to carry out before a -hibernation/suspend or after a restore/resume, requiring the system to be fully -functional, so the drivers' .suspend() and .resume() routines are not suitable -for this purpose. For example, device drivers may want to upload firmware to -their devices after a restore from a hibernation image, but they cannot do it by -calling request_firmware() from their .resume() routines (user land processes -are frozen at this point). The solution may be to load the firmware into -memory before processes are frozen and upload it from there in the .resume() -routine. Of course, a hibernation notifier may be used for this purpose. - -The subsystems that have such needs can register suspend notifiers that will be -called upon the following events by the suspend core: + (C) 2007-2011 Rafael J. Wysocki <rjw@sisk.pl>, GPL + +There are some operations that subsystems or drivers may want to carry out +before hibernation/suspend or after restore/resume, but they require the system +to be fully functional, so the drivers' and subsystems' .suspend() and .resume() +or even .prepare() and .complete() callbacks are not suitable for this purpose. +For example, device drivers may want to upload firmware to their devices after +resume/restore, but they cannot do it by calling request_firmware() from their +.resume() or .complete() routines (user land processes are frozen at these +points). The solution may be to load the firmware into memory before processes +are frozen and upload it from there in the .resume() routine. +A suspend/hibernation notifier may be used for this purpose. + +The subsystems or drivers having such needs can register suspend notifiers that +will be called upon the following events by the PM core: PM_HIBERNATION_PREPARE The system is going to hibernate or suspend, tasks will be frozen immediately. PM_POST_HIBERNATION The system memory state has been restored from a - hibernation image or an error occured during the - hibernation. Device drivers' .resume() callbacks have + hibernation image or an error occurred during + hibernation. Device drivers' restore callbacks have been executed and tasks have been thawed. PM_RESTORE_PREPARE The system is going to restore a hibernation image. - If all goes well the restored kernel will issue a + If all goes well, the restored kernel will issue a PM_POST_HIBERNATION notification. -PM_POST_RESTORE An error occurred during the hibernation restore. - Device drivers' .resume() callbacks have been executed +PM_POST_RESTORE An error occurred during restore from hibernation. + Device drivers' restore callbacks have been executed and tasks have been thawed. -PM_SUSPEND_PREPARE The system is preparing for a suspend. +PM_SUSPEND_PREPARE The system is preparing for suspend. -PM_POST_SUSPEND The system has just resumed or an error occured during - the suspend. Device drivers' .resume() callbacks have - been executed and tasks have been thawed. +PM_POST_SUSPEND The system has just resumed or an error occurred during + suspend. Device drivers' resume callbacks have been + executed and tasks have been thawed. It is generally assumed that whatever the notifiers do for PM_HIBERNATION_PREPARE, should be undone for PM_POST_HIBERNATION. Analogously, diff --git a/Documentation/power/opp.txt b/Documentation/power/opp.txt index cd445582d1f8..5ae70a12c1e2 100644 --- a/Documentation/power/opp.txt +++ b/Documentation/power/opp.txt @@ -178,7 +178,7 @@ opp_find_freq_ceil - Search for an available OPP which is *at least* the if (!IS_ERR(opp)) soc_switch_to_freq_voltage(freq); else - /* do something when we cant satisfy the req */ + /* do something when we can't satisfy the req */ /* do other stuff */ } diff --git a/Documentation/power/swsusp.txt b/Documentation/power/swsusp.txt index ea718891a665..ac190cf1963e 100644 --- a/Documentation/power/swsusp.txt +++ b/Documentation/power/swsusp.txt @@ -192,7 +192,7 @@ Q: There don't seem to be any generally useful behavioral distinctions between SUSPEND and FREEZE. A: Doing SUSPEND when you are asked to do FREEZE is always correct, -but it may be unneccessarily slow. If you want your driver to stay simple, +but it may be unnecessarily slow. If you want your driver to stay simple, slowness may not matter to you. It can always be fixed later. For devices like disk it does matter, you do not want to spindown for @@ -237,7 +237,7 @@ disk. Whole sequence goes like running system, user asks for suspend-to-disk - user processes are stopped (in common case there are none, but with resume-from-initrd, noone knows) + user processes are stopped (in common case there are none, but with resume-from-initrd, no one knows) read image from disk diff --git a/Documentation/power/userland-swsusp.txt b/Documentation/power/userland-swsusp.txt index 81680f9f5909..1101bee4e822 100644 --- a/Documentation/power/userland-swsusp.txt +++ b/Documentation/power/userland-swsusp.txt @@ -98,7 +98,7 @@ SNAPSHOT_S2RAM - suspend to RAM; using this call causes the kernel to The device's read() operation can be used to transfer the snapshot image from the kernel. It has the following limitations: - you cannot read() more than one virtual memory page at a time -- read()s accross page boundaries are impossible (ie. if ypu read() 1/2 of +- read()s across page boundaries are impossible (ie. if ypu read() 1/2 of a page in the previous call, you will only be able to read() _at_ _most_ 1/2 of the page in the next call) @@ -137,7 +137,7 @@ mechanism and the userland utilities using the interface SHOULD use additional means, such as checksums, to ensure the integrity of the snapshot image. The suspending and resuming utilities MUST lock themselves in memory, -preferrably using mlockall(), before calling SNAPSHOT_FREEZE. +preferably using mlockall(), before calling SNAPSHOT_FREEZE. The suspending utility MUST check the value stored by SNAPSHOT_CREATE_IMAGE in the memory location pointed to by the last argument of ioctl() and proceed @@ -147,7 +147,7 @@ in accordance with it: (a) The suspending utility MUST NOT close the snapshot device _unless_ the whole suspend procedure is to be cancelled, in which case, if the snapshot image has already been saved, the - suspending utility SHOULD destroy it, preferrably by zapping + suspending utility SHOULD destroy it, preferably by zapping its header. If the suspend is not to be cancelled, the system MUST be powered off or rebooted after the snapshot image has been saved. |