How to properly invalidate the Pre-Fetch Buffer?

PFB can only be properly invalidated by setting the invalidate prefetch buffer bit (CMMR_SYSCTL.PFB_INVAL = 1) and then clearing it (CMMR_SYSCTL.PFB_INVAL = 0), when the data and instruction port pre-fetch buffers are enabled (CMMR_SYSCTL.DPORT_PFB_EN = CMMR_SYSCTL.IPORT_PFB_EN = 1).