From 3a2d5b700132f35401f1d9e22fe3c2cab02c2549 Mon Sep 17 00:00:00 2001 From: "Rafael J. Wysocki" Date: Sat, 23 Feb 2008 19:13:25 +0100 Subject: PM: Introduce PM_EVENT_HIBERNATE callback state During the last step of hibernation in the "platform" mode (with the help of ACPI) we use the suspend code, including the devices' ->suspend() methods, to prepare the system for entering the ACPI S4 system sleep state. But at least for some devices the operations performed by the ->suspend() callback in that case must be different from its operations during regular suspend. For this reason, introduce the new PM event type PM_EVENT_HIBERNATE and pass it to the device drivers' ->suspend() methods during the last phase of hibernation, so that they can distinguish this case and handle it as appropriate. Modify the drivers that handle PM_EVENT_SUSPEND in a special way and need to handle PM_EVENT_HIBERNATE in the same way. These changes are necessary to fix a hibernation regression related to the i915 driver (ref. http://lkml.org/lkml/2008/2/22/488). Signed-off-by: Rafael J. Wysocki Acked-by: Pavel Machek Tested-by: Jeff Chua Signed-off-by: Linus Torvalds --- Documentation/power/devices.txt | 13 ++++++++----- 1 file changed, 8 insertions(+), 5 deletions(-) (limited to 'Documentation/power') diff --git a/Documentation/power/devices.txt b/Documentation/power/devices.txt index c53d2636191..461e4f1dbec 100644 --- a/Documentation/power/devices.txt +++ b/Documentation/power/devices.txt @@ -310,9 +310,12 @@ used with suspend-to-disk: PM_EVENT_SUSPEND -- quiesce the driver and put hardware into a low-power state. When used with system sleep states like "suspend-to-RAM" or "standby", the upcoming resume() call will often be able to rely on - state kept in hardware, or issue system wakeup events. When used - instead with suspend-to-disk, few devices support this capability; - most are completely powered off. + state kept in hardware, or issue system wakeup events. + + PM_EVENT_HIBERNATE -- Put hardware into a low-power state and enable wakeup + events as appropriate. It is only used with hibernation + (suspend-to-disk) and few devices are able to wake up the system from + this state; most are completely powered off. PM_EVENT_FREEZE -- quiesce the driver, but don't necessarily change into any low power mode. A system snapshot is about to be taken, often @@ -329,8 +332,8 @@ used with suspend-to-disk: wakeup events nor DMA are allowed. To enter "standby" (ACPI S1) or "Suspend to RAM" (STR, ACPI S3) states, or -the similarly named APM states, only PM_EVENT_SUSPEND is used; for "Suspend -to Disk" (STD, hibernate, ACPI S4), all of those event codes are used. +the similarly named APM states, only PM_EVENT_SUSPEND is used; the other event +codes are used for hibernation ("Suspend to Disk", STD, ACPI S4). There's also PM_EVENT_ON, a value which never appears as a suspend event but is sometimes used to record the "not suspended" device state. -- cgit v1.2.3