Hi, On 04/06/2014 07:28 PM, Siarhei Siamashka wrote: > On Fri, 21 Mar 2014 04:27:19 -0700 (PDT) > [email protected] wrote: > >> Am Freitag, 21. März 2014 11:16:04 UTC+1 schrieb Hans de Goede: >>> any objections to me merging this during one of the coming days ? >> >> There was a discussion with Huang Benn who is a member of Cubieboard. >> https://groups.google.com/forum/#!topic/linux-sunxi/rhOUJXJu0Jg >> >> 384 MHz seems to be quit conservative. Huang suggests 432 MHz. > > When I originally submitted this Cubieboard2 dram clock reduction > patch for u-boot, I had a hope that it's only going to be a temporary > solution. And that the hardware manufacturers (CubieTech in this case) > will step in and help us to find the best settings for their hardware > which are also 100% reliable on non-defective units. > > But appears that this is not going to fly. CubieTech is providing > their own SD card images with their own tweaks, which differ from > https://github.com/linux-sunxi/sunxi-boards > OLIMEX is also providing their own SD card images and compilation > instructions, relying on their own extra patches and custom > fex files. Moreover, there is also an active community providing a > variety of their own customized images at http://www.cubieforums.com/ > (with different tweaks, and also overclocking in some cases). We > just can't stop the creativity of all these people :-) > > Anyway, what we have now is that the default Cubieboard2 dram settings > at https://github.com/linux-sunxi/sunxi-boards do not work reliable > out of the box for some small fraction of users. I am *not* one of > them. My Cubietruck works fine with dram clocked at 432MHz and my > Cubieboard2 works fine with 480MHz dram, even with a bit of > overclocking headroom. And to move forward, we need ACKs from the > real users of the problematic hardware. Only they can tell us, which > dram clock speed is good for their devices. But finding a stable > hardware configuration is easier said than done. > > And the only half-decent manageable solution is IMHO the introduction > of diagnostic tools, which could be useful for identifying defective > or misconfigured hardware. I hope that we can start with > https://github.com/ssvb/lima-memtester/ > and evolve it into a more complete stress test suite for the sunxi > hardware (add cpuburn functionality, temperature monitoring and other > bells and whistles). Also trying to make it extremely simple and > intuitive to use. With the goal to eventually enforce something like > the following policy: if you have not run the diagnostic stress > test tool, then you have no right to complain about the supposedly > *software* problems that you think you have on your sunxi device. > > As for the 480MHz dram clock on Cubieboard2, we are currently verifying > if it is just dcdc3 voltage that makes a certain small fraction of > Cubieboard2 devices unstable: > http://irclog.whitequark.org/linux-sunxi/2014-04-04#7013744; > Cubieboard1 and Cubieboard2 are both using exactly the same PCB. > And also Cubieboard1 is known to be 100% reliable with 480MHz dram > clock speed (at least there were no reports about any problems). > This means that the problem is likely in the A20 SoC or its > misconfiguration. And dcdc3 voltage looks like a very likely culprit, > taking into account the test results from my Cubietruck: > https://www.mail-archive.com/[email protected]/msg03510.html >
Thanks for your continued work on this. For now I'll hold back on merging the clock reduction patch until we've some more info on this / some results from your further testing. Regards, Hans -- 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.
