Op 11 mei 2014, om 22:43 heeft Hans de Goede <hdego...@redhat.com> het volgende geschreven:
> Hi, > > On 05/11/2014 11:53 AM, Siarhei Siamashka wrote: >> It has been confirmed that a substantial percentage of cubieboard2 >> and cubietruck users are having stability issues. These issues are >> caused by having various voltages optimistically configured way too >> low. Because each unit has its own tolerances, not everyone can >> easily reproduce these problems. >> >> To address the issue, we take the updated settings from: >> >> https://github.com/cubieboard/cubie_configs/tree/09e511721697/sysconfig/linux >> This repository is relevant because it is referenced from: >> >> http://docs.cubieboard.org/tutorials/ct1/development/compiling_latest_kernel_for_cubietruck_cubieboard3 >> Please note that there is also a sunxi-boards repository fork at >> https://github.com/cubieboard (with bad settings) and this makes >> things more confusing than necessary. >> >> Signed-off-by: Siarhei Siamashka <siarhei.siamas...@gmail.com> >> --- >> sys_config/a20/cubieboard2.fex | 18 +++++++++--------- >> sys_config/a20/cubietruck.fex | 16 ++++++++-------- >> 2 files changed, 17 insertions(+), 17 deletions(-) >> >> diff --git a/sys_config/a20/cubieboard2.fex b/sys_config/a20/cubieboard2.fex >> index 1436df8..c8c9c74 100644 >> --- a/sys_config/a20/cubieboard2.fex >> +++ b/sys_config/a20/cubieboard2.fex >> @@ -1,14 +1,14 @@ >> [product] >> version = "100" >> -machine = "cubieboard" >> +machine = "cubieboard2" >> >> [platform] >> eraseflag = 0 >> >> [target] >> boot_clock = 912 >> -dcdc2_vol = 1400 >> -dcdc3_vol = 1250 >> +dcdc2_vol = 1450 > > This makes no sense, since in the dvfs table there is: > max_freq = 912000000 > > LV2_freq = 912000000 > LV2_volt = 1425 > > S0 1.425 volt would make a lot more sense. Also Page 31 > of A20+Datasheet+v1.0+20130227.pdf says that the MAX > CPU and systemvoltage is 1425 volts. So what this patch > effectively does is overvolt the CPU cores and base system. Keep in mind that the voltage you set is the for for the output pin of the PMIC, *not* the input pin on the CPU. And since this is a 'performance' operating point, the voltage might sag under load. When I was adding 1GHz support to the beagleboneblack DTS the TI hardware team recommended a 2% safety margin, so to get 1425mV into the CPU you need to configure the PMIC for 1425*102% -> 1453mV. I haven't looked at cubieboard schematic nor do I know how accurate the PMIC is, but I wouldn't call this 2% 'overvolting', I'd call it a 'safety margin.' regards, Koen > > Now overvolting is a well know trick when doing overclocking, > the question is do we really want to ship a config which > overvolts by default? > > My first instinctive reaction is no we don't. But if this > cures our stability issues, then I think it makes sense to > do so, in this case u-boot should be changed to init the > cpu voltage to 1.425 volt by default too. > > Note all these new settings significantly exceed the > official allwinner settings / the settings found in > any other a20 device fex file. If we want to make these > changes, we should probably change this for all boards. > > 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 linux-sunxi+unsubscr...@googlegroups.com. > For more options, visit https://groups.google.com/d/optout. -- 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 linux-sunxi+unsubscr...@googlegroups.com. For more options, visit https://groups.google.com/d/optout.
