That first thing I tried with SPI RXONLY mode was not that big of a succes , got OVR errors on non-DMA SPI transactions following the DMA. You can enter any number of items to be transferred into the DMA CNTDR reg but apparently the spi itself is o...

First thing I would try is to switch SPI to unidirectional RXONLY=1 for channel2 and BIDIOE=1 for channel 3. Exceeding maximum throughput is impossible ;) and I would expect the SPI to only clock out new data AFTER a RXNE=0... Let us know what you f...