In the K64, SPI1 and SPI2 have only a single DMA trigger source. As far as I can see, this means you can't operate both a transmit and a receive DMA at the same time. In particular, this means that a DMA receive in Master mode is impossible, since it always requires a transmit channel. Is this true? It seems like a significant step back from, say, the K60, where all SPI channels have separate TX and RX DMA triggers.
Any workaround, except to use polling or interrupts?