Re: [PATCH] xtensa: Fix mmap() support

[Christoph Hellwig]

On Thu, Mar 30, 2017 at 10:30:32AM +0200, Boris Brezillon wrote:
> I think I misunderstood what CONFIG_ARCH_NO_COHERENT_DMA_MMAP means.
> My understanding was that, if CONFIG_ARCH_NO_COHERENT_DMA_MMAP is not
> set, the architecture is assumed to be cache-coherent, but re-reading
> the option name I realize you're probably right.

It just says that the architecture did not support dma_common_mmap at
the point in time when I switched all architectures to use the common
dma_ops or implementing the various dma calls.  There is no inherent
logic behind the symbol, and if the few remaining architectures could
support it with a bit work the option could just go away.