From mboxrd@z Thu Jan 1 00:00:00 1970 From: Arnd Bergmann Subject: Re: [PATCH V2 1/3] scsi: mptxsas: try 64 bit DMA when 32 bit DMA fails Date: Tue, 10 Nov 2015 23:08:57 +0100 Message-ID: <5480219.RxDdMdtxQU@wuerfel> References: <1447034266-28003-1-git-send-email-okaya@codeaurora.org> <4912471.TLsW7CIyYF@wuerfel> <564268B6.9000204@codeaurora.org> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7Bit Return-path: In-Reply-To: <564268B6.9000204@codeaurora.org> Sender: linux-kernel-owner@vger.kernel.org To: Timur Tabi Cc: Sinan Kaya , linux-arm-kernel@lists.infradead.org, Abhijit Mahajan , Nagalakshmi Nandigama , linux-scsi@vger.kernel.org, jcm@redhat.com, "James E.J. Bottomley" , linux-kernel@vger.kernel.org, Sreekanth Reddy , Praveen Krishnamoorthy , cov@codeaurora.org, linux-arm-msm@vger.kernel.org, agross@codeaurora.org, MPT-FusionLinux.pdl@avagotech.com, Hannes Reinecke List-Id: linux-scsi@vger.kernel.org On Tuesday 10 November 2015 15:59:18 Timur Tabi wrote: > On 11/10/2015 03:54 PM, Arnd Bergmann wrote: > > >> In our drivers for 32-bit devices, we have to explicitly set the DMA > >> mask to 32-bits in order to get any DMA working. > > > > Do you mean PCI devices or platform devices? > > Platform. > > > Maybe the parent bus is lacking a dma-ranges property? > > All of this applies only on device-tree platforms. Sinan and I are > working on an ACPI server platform. So we never call > of_dma_configure(), and we don't have a dma-ranges property. ACPI must have something else to mark DMA master devices and their capabilities, right? The platform should initialize the dma_mask pointer to a per-device mask and set both the dma_mask and dma_coherent_mask to 32 bits for any DMA master device, and the device driver should override that to be an appropriate mask based on its needs later. Arnd