Re: Discussion: quick_pit_calibrate is slow

From: George Spelvin
Date: Wed Jun 10 2015 - 12:27:52 EST


Arjan van de Ven <arjanvandeven@xxxxxxxxx> wrote:
> btw one thing to think about; if you calibrate VERY quickly, you need
> to consider spread spectrum clocking.

Excellent point! But spread spectrum clock modulation rates are typically
about 30 kHz, so 1 ms will average over 30 cycles, which should be enough.

The faster the modulation rate, the more the EMI peak is flattened.
But too fast produces unaceptable cycle-to-cycle timing variations,
also known as clock jitter.
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/