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-rw-r--r--Documentation/power/devices.txt14
1 files changed, 9 insertions, 5 deletions
diff --git a/Documentation/power/devices.txt b/Documentation/power/devices.txt
index 1971bcf48a6..88880839ece 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