Thursday, March 28, 2013

Forcing a device driver to a power state for a power manager state

Many of you might already know that in Windows CE 6.0 one can set the device power state to a required power state other than default power state for a particular power manager state.

[HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Power\State\useridle] 
"Default"=dword:1
The above entry will keep all the devices in D1 state while entering into User Idle power manager state 


In Windows CE 6.0 we have following default power manager states

ON, UserIdle, SystemIdle, Resuming, Suspend, Coldreboot and reboot.

Let's say one would like to set a stream interface driver XYZ to D4 while entering into D4 state.

Hence the below registry key has to be specified in platform.reg

[HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Power\State\useridle] 
"xyz1:"=dword:4



Please note that in PM the case for the entry is sensitive. Hence if you set XYZ1 inplace of xyz1 then it will not work. 

Thank You for reading the post.



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