DMA buffer synchronisation with ioremap()

(I go no replies last week, so I'll try again, with less explanation...) If I master a DMA from a PCI device into a main memory buffer allocated with dma_alloc_noncoherent(), I need to synchronise the destination buffer using dma_sync_single_range_for_xxx() before and after the DMA. But if the

DMA buffer synchronisation

Hi, I'm transferring data using DMA from a custom PCI device memory into RAM. Can someone advise me on the correct buffer synchronisation strategy for the following 3 scenarios: Assuming I have three buffers, buf_A, and buf_B, both created using dma_alloc_noncoherent(NULL, 32 * PAGE_SIZE, ...),