Regarding the issue with the input data rate of DFSDM？

[ema]

If DFSDM uses internal parallel data input, such as direct write to input register or DMA writing, what is the maximum frequency of input data in this application?

[TDK]

The DFSDM is competing for bus resources along with everything else in the system and the maximum input frequency will depend on what else the system is doing. For that reason, there is not an exact answer for maximum input frequency.

But generally, the APB bus has plenty of resources and tens of Msps should be doable. Likely faster than whatever process is consuming the output.