libbsd zynqmp cpu freq for slcr calc

Kinsey Moore kinsey.moore at oarcorp.com
Thu Oct 14 14:56:56 UTC 2021


On 10/14/2021 01:40, Chris Johns wrote:
> Hi,
>
> I have come across this define in zynqmp_slcr.h:
>
> #define ZYNQMP_DEFAULT_PS_CLK_FREQUENCY 33333333
>
> What if the cpu freq is changed by a user? If this value still valid?
If CPU frequency scaling is used, I believe this value remains 
unchanged. This is the base clock of the processing subsystem as a whole 
which includes all hard peripherals.
> The CPU frequency is under the control system designer in these parts.

That's correct, this frequency could theoretically be changed by using 
different parts on the board, different dividers somewhere, or probably 
even forcing the PL to somehow generate the clock. This clock value has 
been the same for all 3 ZynqMP boards I have on hand.


Kinsey



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