On 09/28/2014 05:58 PM, Hans de Goede wrote:
My Olimex A10 OLinuXino Lime is also labelled "Rev. A"... It is running stable at 1008MHz and I just tried Olivers djpeg test without any problems.[...]On 09/18/2014 06:07 PM, Siarhei Siamashka wrote:Which revision of A10-OLinuXino-LIME do you have? Revision A is known to have troubles running stable at 1008MHz CPU clock speed, as confirmed on a sample set of two boards (mine and Oliver Schinagl's): https://www.mail-archive.com/linux-sunxi@googlegroups.com/msg04343.htmlI have a revision A board.
I'm running Hans' u-boot-sunxi 2014.10-rc1-g7190869 and Linux mainline 3.17.0-rc1-00158-g451fd72.
I bought my revision A from a German distributor (exp-tech.de) and it doesn't look hand soldered (except for the through hole parts :-) ).A bunch of revision C boards were all fine in Oliver's tests. And nobody has ever tested revision B so far, so we have no idea whether it is stable or not. A mysterious thing is that the Olimex representatives on IRC were not aware of any fixes of this kind applied to the PCB. My understanding is that the revision A was just a small pre-production batch, donated by OLIMEX to a number of open source developers. Some of these boards were distributed at FOSDEM. I'm not sure if we should really worry about the reliability of the revision A, because none of the 'normal' customers probably have such boards. We only need to clarify the status of revision B. But if we want to support the revision A too, then it probably needs its own config, which would somehow restrict the CPU clock speed. I also haMy revision A was actually ordered normally, a couple of days before the first batch sold-out. So it is likely that the entire first batch was revision A. Do you have any easy step-by-step document (or ready to use sdcard image to download) to do some stress tests on my revision A ? Maybe the first couple handed out to developers where hand soldered or some such ? Either way it would be good to either confirm that my revision A has the same issues, or not :)
If I correctly compared the schematics for revision A,B and C, there is only one change in regard to the DRAM: R8 (connected to ZQ) has a different value:
- Revision A: 237 Ohm / 1% - Revision B: 430 Ohm / 1% - Revision C: 330 Ohm / 1%I checked R8 on my revision A's PCB: It is a 330 Ohm / 1%, therefore the value specified in the revision C schematic. So it may make sense to check R8 on the problematic revision A boards and replace it by a 330 Ohm resistor. The DRAM data sheet specifies this resistor with 240 Ohm / 1%...
The current (probably incorrect) values work fine with my board (even though they may be out of spec), but the value of R8 may have some impact here.[...] Either way, these settings are outside of the valid range when running at 480MHz (which would be something like DDR3-960 in our case). [...]
Best regards, Arnd -- Arnd Gronenberg, a...@gronenberg.com, DJ9PZ / AB2QP
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