Timing is VERY critical when using rockbox-psgroove to JB my ps3 firmware 3.15. I have to use very different timings wether i JB using my HD2 or my ipod 4G Greyscale. With my hd2, i let my hd2 boot completely, then connect it on the ps3, power on at the back, switch on/eject. Works every time.
With the ipod it is different, and i was very doubtful when i tried at first (rockbox still not completely loaded while ps3 boots), but it really works :
- Switch of at the back of the ps3 ;
- plug in the ipod while still switched off (both ipod and ps3) ;
- power on ps3 at the back ;
- start rockbox-psgroove then IMMEDIATELY
- switch on / eject ps3
Try this method, it works for me every time!