need help w/ Cora-Z7, XC7Z007S Zynq board

[Thomas Skibo]

On Sat, May 16, 2020 at 11:38:53PM -0700, John-Mark Gurney wrote:
> 
> After a bit of digging, I think I have found the solution.  It looks
> like slcr is suppose to be set to the frequency of the ps clk, which
> is 50 MHz, and then the global_timer is suppose to be set to half the
> CPU clock frequency, which on this board is, I believe, 650 MHz, so
> using the following in the dts made things work:
> &slcr {
> 	clock-frequency = <50000000>;
> };
> 
> &global_timer {
> 	clock-frequency = <325000000>;
> };
> 
> ping times look good sane (after I realized that wifi has a tad slower),
> and I've been running ntpd for over 20 minutes, and it hasn't bombed
> out yet, and the offset/jitter look good.
> 
> -- 
>   John-Mark Gurney				Voice: +1 415 225 5579
> 
>      "All that I will do, has been done, All that I have, has not."
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> 

sysctl hw.zynq will tell you the ARM PLL frequency.  It is probably set
to 1300 Mhz so 325 Mhz is the correct global timer frequency.

--Thomas

-- 

=====
Thomas Skibo
thomas-bsd at skibo.net