When using the DisplayPort application example design (pass-through or RX only), if I change the resolution in my GPU, I cannot see a change on the RX MSA registers.
However, on my monitor (for a pass-through application), I can see that the video resolution is changing.
For example, the video resolution is initially set for 4K. If I change it to 1080p, I can see that there is a zoom in the video stream but the MSA registers still display "Horz Resolution (0x500) : 3840" and "Horz Resolution (0x500) : 2160" (4K resolution).
Why am I seeing this behavior?
Some GPUs are scaling the video stream to avoid retraining every time the resolution change. So in this case, the stream sent by the GPU is actually a 4K stream but which shows a 1080p video. The values from the RX MSA registers are correct.
There are (at least) two ways to confirm if this is what your source is doing:
On some computer, there is an option to avoid the scaling.