On Fri, May 27, 2011 at 3:28 AM, Wolfgang Denk <w...@denx.de> wrote: > Dear Simon Glass, > > In message <BANLkTikWwuymrJtMEHBZkvNgNBK1e=r...@mail.gmail.com> you wrote: >> >> Can we have a microsecond one also please? Some sort of microsecond > > I guess you cannot, at least not in general. In worst case that would > mean we have to process 1e6 interrupts per second, which leaves little > time for anything useful.
If we implemented a sync_us_timer(), we could either: a) Never kick it using an interrupt at all (only kick it in udelay()) b) Kick it in a much slower interrupt (1ms+ period) Remember, the kicking of the sync function does not need to correlate to the incrementing of the tick counter - Only to the roll-over period of the tick counter. For a 64-bit sub microsecond tick counter, interrupts will probably not ever be needed (unless the tick frequency is ludicrous - even a nanosecond tick counter will take 213 days to wrap) so in this case, sync_us_timer() would be fine Regards, Graeme _______________________________________________ U-Boot mailing list U-Boot@lists.denx.de http://lists.denx.de/mailman/listinfo/u-boot
