Hi All, [...] > Looking at the JZ4780_DS.PDF file, the SoC actually wants 1.1V so the > DT is not wrong - in theory. But in practice it does not work, as you > experienced yourself. However, if the ACT8600 defaults to 1.2V, or if > the bootloader configures it to 1.2V, I would think that this is > actually a voltage that the SoC can handle - otherwise the SoC would > be > overvolted until the kernel starts, and the board design would be > flawed. > > I measured that the old 3.x kernel keeps the SoC voltage at 1.2V, so > it > sounds like a better default. Therefore the fix here would be to > raise > the DCDC1 regulator to 1.2V. > > I'll send a patch later today. After a talk with Christophe (Cc'd), I changed my mind. A +100 mV overvolt is a *huge* step up, and although the SoC doesn't burst into flames, it could very well reduce its life span. I used to have huge stability issues (kernel not booting to userspace half the times, or just plain reboots after a few minutes of uptime) and I now realize it's because I was running the core at 1.1V, because these issues disappeared the moment I switched to 1.2V. However, I am now running at 1.125 volts, which is just 25mV above the nominal voltage - and it's been extremely stable so far. Nikolaus: could you test at 1.125 volts? If it's stable for you as well, I'd suggest to use this as the new default. Paul (Burton): As you wrote most of the drivers (and uboot?) for the board, do you know why VDDCORE was set to 1.2V? Cheers, -Paul
