From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S940651AbdAJOC3 (ORCPT ); Tue, 10 Jan 2017 09:02:29 -0500 Received: from mail-lf0-f49.google.com ([209.85.215.49]:34115 "EHLO mail-lf0-f49.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S940517AbdAJOCB (ORCPT ); Tue, 10 Jan 2017 09:02:01 -0500 Subject: Re: [PATCH v2] arm64: do not set dma masks that device connection can't handle To: Robin Murphy , Will Deacon References: <1483947002-16410-1-git-send-email-nikita.yoush@cogentembedded.com> <20170110115132.GD21598@arm.com> <07253eaa-5729-0f15-42b6-e8403f1f0412@cogentembedded.com> <11daacde-5399-039f-80a3-01d7bd13e9e8@arm.com> Cc: Arnd Bergmann , linux-arm-kernel@lists.infradead.org, Catalin Marinas , linux-kernel@vger.kernel.org, linux-renesas-soc@vger.kernel.org, Simon Horman , Bjorn Helgaas , artemi.ivanov@cogentembedded.com, fkan@apm.com From: Nikita Yushchenko Message-ID: <24c5a31e-0148-315b-19b3-0aec456e1164@cogentembedded.com> Date: Tue, 10 Jan 2017 17:01:58 +0300 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:45.0) Gecko/20100101 Icedove/45.5.1 MIME-Version: 1.0 In-Reply-To: <11daacde-5399-039f-80a3-01d7bd13e9e8@arm.com> Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org >> What issue "IOMMU doesn't solve"? >> >> Issue I'm trying to address is - inconsistency within swiotlb >> dma_map_ops, where (1) any wide mask is silently accepted, but (2) then >> mask is used to decide if bounce buffers are needed or not. This >> inconsistency causes NVMe+R-Car cobmo not working (and breaking memory >> instead). > > The fundamental underlying problem is the "any wide mask is silently > accepted" part, and that applies equally to IOMMU ops as well. Is just posted version better? It should cover iommu case as well. Nikita