Hi, On 05/12/2014 09:16 AM, Koen Kooi wrote: > > Op 11 mei 2014, om 22:43 heeft Hans de Goede <[email protected]> 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 <[email protected]> >>> --- >>> 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.
UGH, typo from my side, the data sheet says max voltage is 1.400 > 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.' Ah interesting, so assuming things are similar for the A10 / A20 this would mean that 1.425 volt on the pmic output pin would lead to ~ 1.400 V on the SoC input pin, which is exactly up to spec. Thanks for the insight! 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.
