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| author | Wolfgang Denk <[email protected]> | 2007-04-18 16:06:05 +0200 |
|---|---|---|
| committer | Wolfgang Denk <[email protected]> | 2007-04-18 16:06:05 +0200 |
| commit | 0f5642d7322740ad008a4c5eb0a131d64a6f7a0a (patch) | |
| tree | 129be3feb683cc3b54c259429c5b9fad75f5ffeb /doc | |
| parent | ad4eb555671d97f96dc56eab55103b1f86874b01 (diff) | |
| parent | afc7e4c2a4729427bec672561ea1b3dbb5e8c0d3 (diff) | |
Merge with /home/wd/git/u-boot/custodian/u-boot-ppc4xx
Diffstat (limited to 'doc')
| -rw-r--r-- | doc/README.Lite5200B_low_power | 22 |
1 files changed, 22 insertions, 0 deletions
diff --git a/doc/README.Lite5200B_low_power b/doc/README.Lite5200B_low_power new file mode 100644 index 00000000000..5b04fbba72a --- /dev/null +++ b/doc/README.Lite5200B_low_power @@ -0,0 +1,22 @@ +Lite5200B wakeup from low-power mode (CONFIG_LITE5200B_PM) +---------------------------------------------------------- + +Low-power mode as described in Lite5200B User's Manual, means that +with support of MC68HLC908QT1 microcontroller (refered to as QT), +everything but the SDRAM can be powered down. This brings +maximum power saving, while one can still restore previous state +quickly. + +Quick overview where U-Boot comes into the picture: +- OS saves device states +- OS saves wakeup handler address to physical 0x0, puts SDRAM into + self-refresh and signals to QT, it should power down the board +- / board is sleeping here / +- someone presses SW4 (connected to QT) +- U-Boot checks PSC2_4 pin, if QT drives it down, then we woke up, + so get SDRAM out of self-refresh and transfer control to OS + wakeup handler +- OS restores device states + +This was tested on Linux with USB and Ethernet in use. Adding +support for other devices is an OS issue. |