* Michael Mrozek EvilDragon@openpandora.org [170817 06:38]:
Okay, got some replies from my distributor. The RAM is tested to work with 1.35V.
He's got some ideas though:
- The timings are DIFFERENT when running with 400MHz (DDR3-800) and
often not in the datasheets. If we're running at that speed, we might have to adjust those. The timings can be found on the JEDEC Specification on page 170 and later (I'll send the document to you via Mail, as that's not public).
- Also, if we're running at low speed, the DLL can interfere with the
RAM. This can be disabled via Mode-Register (might be something we can try).
Setting bit 21 to disable ddr3 dll together with termination set to 2 helps with the issue I was seeing where u-boot is having hard time starting. So I'm currently using config value of 0x62a51b3a.
At 1.35V, kernel still keeps hanging all the time during boot so no changes there.
- As it's dual rank, it could be the layout needs to be adjusted (as it
has more load on the lines). However, then I guess it would run unstable at 1.4V as well, wouldn't it?
Anyways, that DLL and the timings are our best guess for now, I think.
I believe we're already using jedec timings. And they work with 1.42V and above.. I don't quite see how the timings would be affected by the voltage?
Regards,
Tony