On Mon, 2018-10-15 at 12:34 +1100, Alexey Kardashevskiy wrote: > On 10/10/2018 00:24, Christoph Hellwig wrote: > > This code has been unused since it was merged and is in the way of > > cleaning up the DMA code, thus remove it. > > > > This effectively reverts commit 5d2aa710 ("powerpc/powernv: Add support > > for Nvlink NPUs"). > > > This code is heavily used by the NVIDIA GPU driver. Some of it is, yes. And while I don't want to be involved in the discussion about that specific can of worms, there is code in this file related to the custom "always error" DMA ops that I suppose we could remove, which is what is getting in the way of Christoph cleanups. It's just meant as a debug stuff to catch incorrect attempts at doing the dma mappings on the wrong "side" of the GPU. Cheers, Ben.