From mboxrd@z Thu Jan 1 00:00:00 1970 From: Christoph Hellwig Subject: Re: [RFC] avoid indirect calls for DMA direct mappings Date: Fri, 7 Dec 2018 02:21:42 +0100 Message-ID: <20181207012141.GA4256@lst.de> References: <20181206153720.10702-1-hch@lst.de> <20181206184330.GB30039@lst.de> <173bfba7-033d-93c4-6ef1-48c9e39c9efc@arm.com> <20181206200006.GA31548@lst.de> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Content-Disposition: inline In-Reply-To: Sender: linux-kernel-owner@vger.kernel.org To: Robin Murphy Cc: Christoph Hellwig , Linus Torvalds , iommu@lists.linux-foundation.org, brouer@redhat.com, tariqt@mellanox.com, ilias.apalodimas@linaro.org, toke@toke.dk, Linux List Kernel Mailing List-Id: iommu@lists.linux-foundation.org On Thu, Dec 06, 2018 at 08:24:38PM +0000, Robin Murphy wrote: > On 06/12/2018 20:00, Christoph Hellwig wrote: >> On Thu, Dec 06, 2018 at 06:54:17PM +0000, Robin Murphy wrote: >>> I'm pretty sure we used to assign dummy_dma_ops explicitly to devices at >>> the point we detected the ACPI properties are wrong - that shouldn't be too >>> much of a headache to go back to. >> >> Ok. I've cooked up a patch to use NULL as the go direct marker. >> This cleans up a few things nicely, but also means we now need to >> do the bypass scheme for all ops, not just the fast path. But we >> probably should just move the slow path ops out of line anyway, >> so I'm not worried about it. This has survived some very basic >> testing on x86, and really needs to be cleaned up and split into >> multiple patches.. > > I've also just finished hacking something up to keep the arm64 status quo - > I'll need to actually test it tomorrow, but the overall diff looks like the > below. Nice. I created a branch that picked up your bits and also the ideas from Linus, and the result looks reall nice. I'll still need a signoff for your bits, though. Jesper, can you give this a spin if it changes the number even further? git://git.infradead.org/users/hch/misc.git dma-direct-calls.2 http://git.infradead.org/users/hch/misc.git/shortlog/refs/heads/dma-direct-calls.2