Minimal support for dm814x
dbrignoli at audioscience.com
Wed Nov 18 00:26:49 PST 2015
On 18 Nov 2015, at 06:22, Matthijs van Duin <matthijsvanduin at gmail.com> wrote:
> The PLL code looks pretty mediocre to me. In particular, they make no
> effort whatsoever to configure an exact ratio. It seems their
> algorithm uses whatever pre divider was already programmed,
I believe the implementors assumed the bootloader was setting up the PLL, its adjustment may have been an afterthought added in order to support PTP.
> This works in principle, but both minimizing the DCO and (often
> needlessly) using the fractional multiplier seem like recipes to
> maximize the clock jitter. Mind you, I don't know how much jitter
> we’re talking about here, I don't recall having seen specs about this.
We haven’t seen any specs either but testing shows that changing DCO mode causes the PLL to lose lock at least temporarily.
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