libbsd zynqmp cpu freq for slcr calc

[Chris Johns]

On 15/10/21 5:33 am, Kinsey Moore wrote:
> On 10/14/2021 10:18, Joel Sherrill wrote:
>> On Thu, Oct 14, 2021 at 9:56 AM Kinsey Moore <kinsey.moore at oarcorp.com> wrote:
>>> 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.
>> If it can be changed by a user, should it be something that can be overridden
>> by configuration?
> 
> Yes, but it hasn't come up yet and so allowing for an override hasn't been a
> priority. 

Agreed. I found after I had asked the question the zynq had the same value.

> This might be one of those things that is best configured in RTEMS
> since it's BSP-related configuration pertaining to a device, but would appear to
> be dead code/configuration since nothing there uses it.

Yeap. At least it is noted now.

Chris