On Mon, Nov 23, 2009 at 7:19 PM, John Watlington <[email protected]> wrote: > > On Nov 23, 2009, at 1:55 PM, Tiago Marques wrote: > >> On Sun, Nov 22, 2009 at 8:01 PM, Mitch Bradley <[email protected]> wrote: >>> >>> Tiago Marques wrote: >>>> >>>> Hi, >>>> >>>> The hardware page for the XO 1.5 doesn't show the clockspeed of the >>>> RAM chips used. CAS 3 looks like very aggressive timings for cheap >>>> DDR2 chips. >>> >>> CL3 is in spec for the chips that we were using but not for a new chip >>> that >>> we might start using. >>> >>>> Are you running at 400 or 533? >>> >>> 400 >>>> >>>> Doesn't the datasheet specify the appropriate timings? >>>> >>> >>> Of course it does. The jumper is to tell which timing set to use, >>> depending >>> on which chips are populated. >> >> Ok, I was rather confused when I read: >> >> "I switched the timing to CAS latency 4 (from 3), which ** should meet >> ** specs for this chip." >> >> And was finding rather odd that you didn't had access to specified >> timings. > > We have access to the chip timings, and we have information about how > to program the controller. But it is still a trial and error process. > Nobody likes to manually verify that the programmable DRAM controller is > actually correctly generating the literally hundreds of timing specs for a > given chip. We instead make our best guess at correct values and then > test for proper operation across time and temperature. > > In this case, the chips usually worked with the CAS latency set too low. > > wad > >
Ok, I see. Any chance that that procedure might be causing issues related to those errors being generated by overheating problems with B2 hardware? I haven't heard if that has been fixed already. Was it? My 1.5 B2 crashed yesterday in a rather unexplicable fashion and gave me some bad data corruption. Haven't been able to reproduce it though, but it seemed high workload related since I was compiling some packages on an FS in the external SD. Will try to find out more about this. Best regards, Tiago Marques _______________________________________________ Devel mailing list [email protected] http://lists.laptop.org/listinfo/devel
