Re: Minimal support for dm814x

[Delio Brignoli <dbrignoli@audioscience.com>]

On 18 Nov 2015, at 06:22, Matthijs van Duin <matthijsvanduin@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.

—
Delio