In SDK's plash example as part of internal flash manipulation routines, you also ivalidate L1 and FtFx caches :
/* Post-preparation work about flash Cache/Prefetch/Speculation. */
is this are mandatory operations if caches is NOT going to be initialised at all.
Those flash routines going to be used in custom bootloader what flash new firmware to some space
and jump to it.
Any extra performance is no need and for simplify bootloader is possible to disable OR no init any code cache
at all ?
Or those code cache operations must to be activated and used as in example ?
There isn't any initialization code for the cache, by default the flash module uses the flash cache, so you have to disable the cache explicitly
Could you please check the following document in this link ? I would recommend you to check especially the section 4.4 Cache coherency in recommended actions for the case of flash operations erase/program.
Hope it helps