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| author | Kim Phillips <kim.phillips@freescale.com> | 2007-04-23 15:58:17 -0500 |
|---|---|---|
| committer | Kim Phillips <kim.phillips@freescale.com> | 2007-04-23 15:58:17 -0500 |
| commit | 396955fed24c301701c83558fc6f7eadd909397b (patch) | |
| tree | e022bf6f768718ce06a29280f3dfa3a0a60f90f3 /doc/README.Lite5200B_low_power | |
| parent | 6fbf261f8df294e589cfadebebe5468e3c0f29e9 (diff) | |
| parent | 14da5f7675bbb427c469e3f45006e027b6e21db9 (diff) | |
| download | u-boot-imx-396955fed24c301701c83558fc6f7eadd909397b.zip u-boot-imx-396955fed24c301701c83558fc6f7eadd909397b.tar.gz u-boot-imx-396955fed24c301701c83558fc6f7eadd909397b.tar.bz2 | |
Merge git://www.denx.de/git/u-boot
Diffstat (limited to 'doc/README.Lite5200B_low_power')
| -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 0000000..5b04fbb --- /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. |