From mboxrd@z Thu Jan 1 00:00:00 1970 From: Christoph Hellwig Subject: Re: [PATCH 03/14] x86: use dma-direct Date: Thu, 15 Mar 2018 12:53:48 +0100 Message-ID: <20180315115348.GA16210@lst.de> References: <20180314175213.20256-1-hch@lst.de> <20180314175213.20256-4-hch@lst.de> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 8bit Return-path: Content-Disposition: inline In-Reply-To: Sender: linux-kernel-owner@vger.kernel.org To: Thomas Gleixner Cc: Christoph Hellwig , x86@kernel.org, Konrad Rzeszutek Wilk , Tom Lendacky , David Woodhouse , Muli Ben-Yehuda , Jon Mason , Joerg Roedel , iommu@lists.linux-foundation.org, linux-kernel@vger.kernel.org List-Id: iommu@lists.linux-foundation.org On Thu, Mar 15, 2018 at 09:56:13AM +0100, Thomas Gleixner wrote: > On Wed, 14 Mar 2018, Christoph Hellwig wrote: > > > The generic dma-direct implementation is now functionally equivalent to > > the x86 nommu dma_map implementation, so switch over to using it. > > Can you please convert the various drivers first and then remove the > unused code? Which various drivers? > > Note that the various iommu drivers are switched from x86_dma_supported > > to dma_direct_supported to provide identical functionality, although the > > checks looks fairly questionable for at least some of them. > > Can you please elaborate? From the above it's not clear which checks you > are referring to. If you convert these drivers seperately then explicit > information about your concerns wants to be in the changelogs. This bit: /* Copied from i386. Doesn't make much sense, because it will only work for pci_alloc_coherent. The caller just has to use GFP_DMA in this case. */ if (mask < DMA_BIT_MASK(24)) return 0; in x86_dma_supported, or the equivalent bit in dma_direct_supported. Kept for bug to bug compatibility, but I guess I should reword or just drop the changelog bit іf it causes confusion.