Significant power savings during framebuffer blanking

As I've posted today to openmoko-kernel, there have been some quite significant power savings during the "backlight off but still not suspended yet" operational mode of the GTA02. The power savings are in the order of 49%, which is really massive, particularly for applications that run in the background while the screen is blanked, like typical mp3/ogg player applications.

It is sad to me that something like this is found long after the GTA02 has actually shipped. It seems like there are still fairly low-hanging fruit around to do some significant power saving.

Since all the measurements can be done on the device itself, using the built-in high precision coulomb counter of the battery, everyone is able to do the measurements without any special equipment. It also means that power management related issues can be tested automatically.

I would love to see somebody working on software that switches certain hardware on (and off) again or cycles through various differnent power states of every hardware unit an then reads the power consumption. The resulting readings can then be manually checked if they're consistent with expectations based on the hardware design. Furthermore, this program could be used for regression testing against new uboot/kernel/OS releases in order to ensure we don't get into power consumption regressions.