Hi, On 15/03/18 11:24, Martin Lucina wrote: > Hi, > > On Thursday, 15.03.2018 at 09:34, Andre Przywara wrote: >> So that might be a DRAM issue then. >> Can you try to lower the frequency? >> Just set CONFIG_DRAM_CLK in your U-Boot .config (or _defconfig) to 648 >> for a start, or try lower values in 24MHz steps. The default value for >> A64 boards is 672 MHz. > > 648 MHz seems to have helped a lot, I've done several warm and cold boots > and only seen the BUG once so far. Will try lowering the frequency further
Cool! I see other Allwinner boards using 624 MHz, so that might be a sweet spot. Alternatively you could also try 408 MHz, which should work everywhere. I really wonder if this is about the PCB delay lines. So far we were getting away with the Pine64(?) values for other boards as well, but the Olimex board might be substantially different in the PCB layout. > and also load the board up with a kernel compile or something (the lima > memtest mentioned by Ondrej depends on the GPU so that's not useful to me > right now). Yeah, I know that Limatester is very helpful, but only works easily with BSP kernels, AFAIK. Which is a shame, I wonder if either someone ports this to something useable with mainline or we actually have a stress test that works without MALI. >> And somewhat related: Can you please check the actual DRAM chips? Find >> the actual name on them (and add them to the linux-sunxi wiki [1] on the >> way), ideally also find a data sheet? >> The DRAM setup code in U-Boot assumes certain chips, also has some >> assumptions about PCB specific values, so the board might need more >> adjustment here. > > Following the link on the linux-sunxi Wiki page, there is a BOM for my (Rev > D) board at [1], which matches the parts that are actually on the board. > I've found what looks like a datasheet for the DRAM part at [2]; I know > nothing about DRAM initialisation so have no idea where to find the correct > frequency to use in that document. Thanks, that very helpful! So it looks like these are actually even 800MHz capable chips. But either this requires some tuning on the PCB delays or the voltage is wrong (as on the Pine64, where we fix this). I will add some code to print the actual DRAM voltage in ATF, will send you something for testing later tonight. Cheers, Andre. > [1] > https://github.com/OLIMEX/OLINUXINO/blob/master/HARDWARE/A64-OLinuXino/A64-OLinuXino_Rev_D/A64-OlinuXino_Rev_D_1G4GW.csv > > [2] http://www.datasheetspdf.com/pdf/970821/Samsung/K4B4G1646Q/1 > -- You received this message because you are subscribed to the Google Groups "linux-sunxi" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. For more options, visit https://groups.google.com/d/optout.
