On Fri, Jul 23, 2021 at 3:40 PM Atish Patra <atish.patra@xxxxxxx> wrote: > > Currently, linux,dma-default is used to reserve a global non-coherent pool > to allocate memory for dma operations. This can be useful for RISC-V as > well as the ISA specification doesn't specify a method to modify PMA > attributes or page table entries to define non-cacheable area yet. > A non-cacheable memory window is an alternate options for vendors to > support non-coherent devices. "dma-ranges" must be used in conjunction with > "linux,dma-default" property to define one or more mappings between device > and cpu accesible memory regions. 'dma-ranges' applies to buses. And, well, maybe devices when the bus is not well defined. It is not a reserved-memory property. Rob
