On Friday, October 18, 2013 10:25:27 AM UTC-7, Siarhei Siamashka wrote: > http://irclog.whitequark.org/linux-sunxi/2013-07-29#4520613; > > > > 10:10 <Tsvetan> the reason we made 384Mhz image is, because when we had enough > > boards produced > > 10:10 <Tsvetan> we noticed that 20% of A20 boards fail on clock more than > 400Mhz > > 10:11 <Tsvetan> replacing the A20 chips on them make them alive > > 10:11 <Tsvetan> which made us think that A20 chips have some tolerances and > > not all can run above 400Mhz > > 10:11 <wingrime> Tsvetan: хи > > 10:11 <Tsvetan> I ask Tom and he observed the same > > 10:11 <Tsvetan> so we decided to generate images with 384 to be on the > > safe side to all boards > > 10:12 <Tsvetan> 80% of the boards still can run up to 480Mhz > > 10:12 <Tsvetan> btw datasheet say nothing for max safe frequency > > 10:12 <Tsvetan> we found this in fiel > > 10:12 <wingrime> Tsvetan: we still not have any auto testing framework > > 10:12 <Tsvetan> field > > 10:12 <oliv3r> wingrime: you mean for dram timings? > > 10:13 <wingrime> oliv3r: yex, some mistery > > 10:13 <Tsvetan> so running at 400-432-480 may work > > 10:13 <oliv3r> i guess it's with overlcocking a PC, you get it with a safe > > setting, and then overclock it to whatever works for you > > 10:13 <Tsvetan> but you do not know what tolerances your chips have > > 10:13 <Tsvetan> and when it will fail infield > > 10:13 <wingrime> Tsvetan: are you using same dram ic ? > > 10:13 <oliv3r> Tsvetan: so cubieboard2 also runs at 384 MHz by default now? > > 10:13 <Tsvetan> same memory chips > > 10:13 <Tsvetan> BTW A10 chips do not suffer this problem > > 10:14 <Tsvetan> and work fine on same layout up to 480Mhz > > 10:14 <Tsvetan> so its up to you at what memory clock you want to run your > board > > 10:14 <Tsvetan> our statistic though says to stay at 384 to be on the safe > side > > 10:15 <oliv3r> better safe then sorry ;) > > > > The 480MHz dram clock frequency has been also confirmed to cause problems > > for at least one user at www.cubieforums.com when running Qt5. > > > > Signed-off-by: Siarhei Siamashka <[email protected]> > > --- > > board/sunxi/dram_cubieboard2.c | 2 +- > > 1 file changed, 1 insertion(+), 1 deletion(-) > > > > diff --git a/board/sunxi/dram_cubieboard2.c b/board/sunxi/dram_cubieboard2.c > > index 370a3d9..287673c 100644 > > --- a/board/sunxi/dram_cubieboard2.c > > +++ b/board/sunxi/dram_cubieboard2.c > > @@ -4,7 +4,7 @@ > > #include <asm/arch/dram.h> > > > > static struct dram_para dram_para = { > > - .clock = 480, > > + .clock = 384, > > .type = 3, > > .rank_num = 1, > > .density = 4096, > > -- > > 1.8.1.5
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