Ran into issues where large buffer, were not fully outputting the right data.
Was seeing it on RA8876 on pages from DMAMEM and at times EXTRAM.
Turns out where I did the arm_dcache_flush (or delete) I had already decreased the count to be the max size I could output in any one DMA operation without chain... So now do it before we check for MAX size...
Appears to fix the display issue I was seeing