On Mon, Aug 18, 2008 at 07:52:12AM -0400, [EMAIL PROTECTED] wrote: > We've got an 8347 based board very similar to the A&M asp8347. Core clock > is 400MHz. Bus clock is 266666666Hz. > According to the data sheet for the 8347, the decrementer clock runs at a > quarter of the rate of the bus clock. I have two questions: > In arch/powerpc/boot/redboot-83xx.c, the timebase clock is passed to > dt_fixup_cpu_clocks() as bi_busfreq / 16. If I leave it like this, my > system clock runs approximately 4 times too fast. > Can anyone point me in the direction of an explanation for the div by 16 > rather than 4?
It's a bug, which I pointed out here: http://ozlabs.org/pipermail/linuxppc-dev/2008-June/058704.html > If I change the call to dt_fixup_cpu_clocks so that bi_busfreq/4 is passed > in, then the clock runs more accurately. However, its still not correct. > This gives a decrementer frequency of 66666666Hz, but if I hard code the > value to 66000000Hz, the clock runs accurately. > Can anyone shed any light on why the value passed in by the boot loader > (redboot) seems to be inaccurate. Redboot probably has the wrong crystal frequency hardcoded. -Scott _______________________________________________ Linuxppc-dev mailing list Linuxppc-dev@ozlabs.org https://ozlabs.org/mailman/listinfo/linuxppc-dev
