http://rhombus-tech.net/rock_chips/rk3288/news/
i now have 2 assembled PCBs with the exact same "fault" - which after talking to paulk and akaka on #linux-rockchip i *may* have a lead on how to get the DDR3 RAM up and running properly. we believe it's down to the impedance control register (ZQCR) which is being hard-coded in u-boot-rockchip rather than being allowed to "train". those values are suited for 6-layer 1.6mm PCBs - the impedance of tracks when you have an 8-layer 1.2mm PCB are *half* what they are for 6-layer 1.6mm PCBs.
l.
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