Why does the reference manual of MPC5607B state that one should not write into DSPIx_RSER while the DSPI is running. If I want to disable one interrupt, why should I halt the entire module at first and not disable it by directly writing in RSER?
Writing to the DSPIx_RSER should not be done while DSPI is running to avoid losing of ISR or DMA request, I think.
If DSPI is in running state you should not write to any configuration register, also to DSPIx_RSER.
When DSPI is in stopped state there should be no issue to modify it. The TXRXS bit in the DSPIx_SR can be used to determine the DSPI state.