From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754072AbdGJPb7 (ORCPT ); Mon, 10 Jul 2017 11:31:59 -0400 Received: from foss.arm.com ([217.140.101.70]:37018 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753646AbdGJPb6 (ORCPT ); Mon, 10 Jul 2017 11:31:58 -0400 Subject: Re: [PATCH/RFC] dma-mapping: Provide dummy set_dma_ops() for NO_DMA=y To: Christoph Hellwig , Geert Uytterhoeven Cc: Marek Szyprowski , Madalin Bucur , "David S . Miller" , Arnd Bergmann , netdev@vger.kernel.org, linux-kernel@vger.kernel.org References: <1499628825-16260-1-git-send-email-geert@linux-m68k.org> <20170710145641.GC7971@lst.de> From: Robin Murphy Message-ID: <6323dd71-0bd3-5823-3837-da84dfba46fe@arm.com> Date: Mon, 10 Jul 2017 16:31:54 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.2.1 MIME-Version: 1.0 In-Reply-To: <20170710145641.GC7971@lst.de> Content-Type: text/plain; charset=utf-8 Content-Language: en-GB Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 10/07/17 15:56, Christoph Hellwig wrote: > This looks reasonable to me, I'd be happy to pick it up. Can you send > it as a series with the reverts? The fact remains that the FSL driver is still doing the wrong thing though - set_dma_ops(dev1, get_dma_ops(dev2)) is just a hack which happens to work on platforms which don't keep other arch-internal DMA info as well. I did start writing a patch somewhere to fix this thing to actually do proper DMA configuration (originally in the context of not abusing arch_setup_dma_ops()), but Arnd's fix is probably simpler. I don't think it makes an awful lot of sense for code without a DMA API dependency to be calling set_dma_ops() - AFAIU the only reason it's available to drivers at all is for particular RDMA cases which know that their "DMA" is actually done by CPU threads, and want to optimise for that. Robin.