FS#10714 - iPod Nano 2G battery life improvements, clock scaling and undervolting
Opened by Michael Sparmann (TheSeven) - Saturday, 24 October 2009, 00:42 GMT
Last edited by Michael Sparmann (TheSeven) - Thursday, 11 March 2010, 02:30 GMT
Here is a patch that tries to reach Apple's battery runtime...
It's scaling the clock from 47923200Hz to 191692800Hz (yes, these frequencies are weird, but they are correct!) and undervolt the CPU core to 1.000V at the high and 0.900V at the low freq.
There are some known issues:
- After USB was connected, you'll need to reboot your ipod, or it will keep the USB controller enabled, which sucks far more current than the backlight.
- Battery_bench is currently broken for Nano2G, I'm looking into fixing this.
- On my iPod, the CPU core could be undervolted to at least 0.800V, but the main system clock started to get unstable at 0.875V, with a significant frequency drop. This results in clearly noticable pitch changes while playing music, when it's boosting/unboosting. Please watch out for this and report it if you have an iPod that is still doing such things at 0.900V.
- I'm also not sure about the upper voltage, my CPU seemed to work fine at 0.975V at the high freq, but I added a small safety margin here.
Please test this and report any instabilites, crashes or other weird behavior, that does only turn up if this patch is applied.
Thursday, 11 March 2010, 02:30 GMT
Reason for closing: Fixed
Additional comments about closing: A different approach has been committed