From mboxrd@z Thu Jan 1 00:00:00 1970 From: Christoph Hellwig Subject: Re: [PATCH v2 3/4] iommu/dma-iommu: Use the dev->coherent_dma_mask Date: Tue, 30 Apr 2019 04:32:53 -0700 Message-ID: <20190430113253.GA23210@infradead.org> References: <20190430002952.18909-1-tmurphy@arista.com> <20190430002952.18909-4-tmurphy@arista.com> <20190430111222.GA3191@infradead.org> 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 , Tom Murphy , iommu@lists.linux-foundation.org, Heiko Stuebner , Will Deacon , David Brown , Thierry Reding , linux-s390@vger.kernel.org, linux-samsung-soc@vger.kernel.org, Krzysztof Kozlowski , Jonathan Hunter , linux-rockchip@lists.infradead.org, Kukjin Kim , Gerald Schaefer , Andy Gross , linux-tegra@vger.kernel.org, linux-arm-msm@vger.kernel.org, linux-mediatek@lists.infradead.org, Matthias Brugger , linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, murphyt7@tcd.i List-Id: linux-tegra@vger.kernel.org On Tue, Apr 30, 2019 at 12:27:02PM +0100, Robin Murphy wrote: > > Hmm, I don't think we need the DMA mask for the MSI mapping, this > > should probably always use a 64-bit mask. > > If that were true then we wouldn't need DMA masks for regular mappings > either. If we have to map the MSI doorbell at all, then we certainly have to > place it at an IOVA that the relevant device is actually capable of > addressing. Well, as shown by the patch below we don't even look at the DMA mask for the MSI page - we just allocate from bottom to top.