Re: RTC_PIE possible using via-pmu?
> > Oh, those periodic interrupt things are features of x86 RTC chips, they
> > aren't available on other architectures, at least not all of them,
> > definitely not on pmac.
>
> Well I was wondering if I could use the via-pmu timer to implement such
> a periodic interrupt.
I wouldn't recommend doing that, and I wouldn't recommend touching the
via-pmu driver at all anyway, it's enough of a mess. Also, the VIA
timers tend not to be very well calibrated on modern HW.
> > Why not just normal timers ?
>
> Not sure what exactly you mean by "normal". I created a genrtc patch [1] for
> the ioctls above using add_timer().
> But the resulting timer responses using a simple test program [2] are not
> that good (the last percentage is the accuracy), and above 1024Hz completely
> unusable:
Yah, you would probably need the high res timer. It would be possible to
do something with the KeyLargo timer maybe...
> Oddly enough (well, odd to me :), 1024Hz is quite good. I have been able
> to do some latency tests with that setting [3] which point to latency issues
> with the radeon and/or drm modules.
> If I get those figured out (video is NOT my area) I'll be kinda stuck.
The kernel is running internally it's scheduler at 1000Hz on ppc, and
thus that's the best precision you'll get, around the ms. You may want
to look into the high resolution timers patches.
> Hints/tips/suggestions welcome... Must say 2.6.11 looks better than 2.6.8.
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