Flickering screen, connecting ethernet cable does not work, clarification for the second workaround

[nicksavul]

First of all, my apologies, perhaps github issues is not the best place to ask this as it's likely my own understanding is at fault rather then the code.

I'm using this vhdl hdmi transmitter as a part of experimental setup for my Bachelor's thesis and cannot get the flickering to go away.

As per instructions from readme I have tried plugging ethernet cable to the board (PYNQ-Z2). This did not stop the flickering. I assumed that perhaps the ethernet cable must be grounded so I have connected the other end to a working network switch (to no avail).

I then attempted to use other suggested fix, which is "source the clock from ZYNQ IO PLL". I'm not very knowledgable about VHDL but my initial assumption was that this meant swapping clock signal used to drive PLLE_BASE from the external oscillator located on the board and connected to FPGA die via io pin to an internal oscillator. After some research I could not find any mention of internal socillators in ZYNQ XC7Z020-1CLG400C SoC. I thought that ZYNQ IO PLL may refer to premade vhdl component however the closest thing I've found was the clocking wizard IP in vivado framework. It however also needs a driver clock. I thought that perhaps passing the extrenal clock to the clocking wizzard (with no scaling) and feeding the output to PLLE_BASE in place might fix the issue, however that was also not the case.