[PATCH] arm64: dma-mapping: Fix dma_mapping_error() when bypassing SWIOTLB

[Michael Zoran]

On Wed, 2017-01-25 at 12:03 +0000, Robin Murphy wrote:
> hen bypassing SWIOTLB on small-memory systems, we need to avoid
> calling
> into swiotlb_dma_mapping_error() in exactly the same way as we avoid
> swiotlb_dma_supported(), because the former also relies on SWIOTLB
> state
> being initialised.
> 

I didn't submit the initial ARM64 port of the RPI 3, so I don't know
much about this.  But from a third personal point of view, this seems
to side step the main issue here.

>From an ARM64 subsystem point of view, what exactly is the
correct/recommended method for ensuring the mm subsystem is initialized
correctly?