diff options
Diffstat (limited to 'Documentation/driver-model')
| -rw-r--r-- | Documentation/driver-model/driver.txt | 60 |
1 files changed, 2 insertions, 58 deletions
diff --git a/Documentation/driver-model/driver.txt b/Documentation/driver-model/driver.txt index fabaca1..7c26bfa 100644 --- a/Documentation/driver-model/driver.txt +++ b/Documentation/driver-model/driver.txt @@ -196,67 +196,11 @@ it into a supported low-power state. int (*suspend) (struct device * dev, pm_message_t state, u32 level); -suspend is called to put the device in a low power state. There are -several stages to successfully suspending a device, which is denoted in -the @level parameter. Breaking the suspend transition into several -stages affords the platform flexibility in performing device power -management based on the requirements of the system and the -user-defined policy. - -SUSPEND_NOTIFY notifies the device that a suspend transition is about -to happen. This happens on system power state transitions to verify -that all devices can successfully suspend. - -A driver may choose to fail on this call, which should cause the -entire suspend transition to fail. A driver should fail only if it -knows that the device will not be able to be resumed properly when the -system wakes up again. It could also fail if it somehow determines it -is in the middle of an operation too important to stop. - -SUSPEND_DISABLE tells the device to stop I/O transactions. When it -stops transactions, or what it should do with unfinished transactions -is a policy of the driver. After this call, the driver should not -accept any other I/O requests. - -SUSPEND_SAVE_STATE tells the device to save the context of the -hardware. This includes any bus-specific hardware state and -device-specific hardware state. A pointer to this saved state can be -stored in the device's saved_state field. - -SUSPEND_POWER_DOWN tells the driver to place the device in the low -power state requested. - -Whether suspend is called with a given level is a policy of the -platform. Some levels may be omitted; drivers must not assume the -reception of any level. However, all levels must be called in the -order above; i.e. notification will always come before disabling; -disabling the device will come before suspending the device. - -All calls are made with interrupts enabled, except for the -SUSPEND_POWER_DOWN level. +suspend is called to put the device in a low power state. int (*resume) (struct device * dev, u32 level); -Resume is used to bring a device back from a low power state. Like the -suspend transition, it happens in several stages. - -RESUME_POWER_ON tells the driver to set the power state to the state -before the suspend call (The device could have already been in a low -power state before the suspend call to put in a lower power state). - -RESUME_RESTORE_STATE tells the driver to restore the state saved by -the SUSPEND_SAVE_STATE suspend call. - -RESUME_ENABLE tells the driver to start accepting I/O transactions -again. Depending on driver policy, the device may already have pending -I/O requests. - -RESUME_POWER_ON is called with interrupts disabled. The other resume -levels are called with interrupts enabled. - -As with the various suspend stages, the driver must not assume that -any other resume calls have been or will be made. Each call should be -self-contained and not dependent on any external state. +Resume is used to bring a device back from a low power state. Attributes |