Re: use generic DMA mapping code in powerpc V4

From: Christoph Hellwig
Date: Sun Dec 16 2018 - 11:52:02 EST

FYI, given that we are one week before the expected 4.20 release
date and I haven't found the bug plaging Christians setups I think
we need to defer most of this to the next merge window.

I'd still like to get a few bits in earlier, which I will send out
separately now.