The of_dma_is_coherent() helper parses the given DT device node to see if the "dma-coherent" property is supported and returns true or false accordingly. If the arch is always coherent or always noncoherent, then the default DMA ops has to be specified accordingly. Cc: Greg Kroah-Hartma...
I am curious to know if DMA writes to coherent memory (allocated by dma_alloc_coherent) by PCIe device are re-ordered somehow e.g. PCH reorders