Minimal support for dm814x

[Tony Lindgren]

* Delio Brignoli <dbrignoli at audioscience.com> [151110 02:24]:
> On 10 Nov 2015, at 09:50, Matthijs van Duin <matthijsvanduin at gmail.com> wrote:
> > On 9 November 2015 at 16:06, Tony Lindgren <tony at atomide.com> wrote:
> >> The PLL support is still missing, so it relies on the bootloader
> >> configured PLL values for now. I'm hoping to post PLL support patches over
> >> next few weeks and then we can have that and more devices working for v4.5.
> > 
> > Ah, yes, configuring a DPLL-LJ is fun.. figuring out how to write the
> > desired ratio as M/(M2*(1+N)) while simultaneously satisfying all
> > constraints on M, N, M2, refclk, and dco. :-)
> 
> Yes, indeed. We have the additional requirement of being able to adjust the frequency (by a relatively small amount) without loss of lock. Recalculating the DCO mode and M,N,M2 from scratch each time based on the target frequency, like was done in the 2.6.37 based tree from TI was not acceptable, so we try to change m2 first to see if we can reach the target frequency and fall back to recalculate parameters from scratch if that fails.

Well we do first try to set the rate using the divider only at least for
drivers/clk/ti/fapll.c used on dm816x. I'm thinking about doing a similar
driver for the dm814x adpll where we have a PLL and separate output clocks
in a single driver as the PLL and output control registers are all mixed
in.

> BTW, are you aware of section 2.1.2 of “TMS320DM814x DaVinci Digital Media Processors Silicon Revisions 3.0, 2.1”? <http://www.ti.com/lit/er/sprz343c/sprz343c.pdf>

OK good to know :)

Tony