Can I use a PS generated clock to drive the VCU reference clock?
The VCU requires an external reference clock.
There are no restrictions when selecting the Global Clock pin for the reference clock.
It is possible to use a PL MMCM to generate the VCU PLL Reference clock if needed, but it is not permissible to have a PS to PL clock as it contains too much jitter.
Additional details, including the ref clock range can be found in (PG252) under the PLL Overview.
The user needs to provide a proper reference clock for the PLL and connect it up in the Linux Device Tree.
The VCU drivers will handle the rest of the settings for the PLL.