From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756357AbcJGIMK (ORCPT ); Fri, 7 Oct 2016 04:12:10 -0400 Received: from userp1040.oracle.com ([156.151.31.81]:43459 "EHLO userp1040.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756290AbcJGIKE (ORCPT ); Fri, 7 Oct 2016 04:10:04 -0400 Subject: Re: [RFC PATCH 6/6] sparc64: Enable 64-bit DMA To: Christoph Hellwig References: <1475796816-14448-1-git-send-email-tushar.n.dave@oracle.com> <1475796816-14448-7-git-send-email-tushar.n.dave@oracle.com> <20161007073252.GA8290@infradead.org> Cc: davem@davemloft.net, chris.hyser@oracle.com, sowmini.varadhan@oracle.com, vgupta@synopsys.com, robin.murphy@arm.com, jroedel@suse.de, egtvedt@samfundet.no, krzk@kernel.org, sparclinux@vger.kernel.org, linux-kernel@vger.kernel.org From: tndave Message-ID: <4a70e648-a854-55d1-54ac-313b84841d04@oracle.com> Date: Fri, 7 Oct 2016 01:09:15 -0700 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:45.0) Gecko/20100101 Thunderbird/45.2.0 MIME-Version: 1.0 In-Reply-To: <20161007073252.GA8290@infradead.org> Content-Type: text/plain; charset=windows-1252; format=flowed Content-Transfer-Encoding: 7bit X-Source-IP: aserv0022.oracle.com [141.146.126.234] Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 10/07/2016 12:32 AM, Christoph Hellwig wrote: > On Thu, Oct 06, 2016 at 04:33:36PM -0700, Tushar Dave wrote: >> ATU 64bit addressing allows PCIe devices with 64bit DMA capabilities >> to use ATU for 64bit DMA. > > Any chance to always enable this? Last I checked sparc was the only > architecture still using a 32-bit dma_addr_t, leading to some fun > breakage in things like the software RDMA drivers that abuse it to > store a kernel pointer.. With change made by patch 6/6, dma_addr_t is always 64-bit, no matter if device DMA mask is 32-bit (i.e. using existing IOMMU) or 64-bit (i.e using ATU) -Tushar > From mboxrd@z Thu Jan 1 00:00:00 1970 From: tndave Date: Fri, 07 Oct 2016 08:09:15 +0000 Subject: Re: [RFC PATCH 6/6] sparc64: Enable 64-bit DMA Message-Id: <4a70e648-a854-55d1-54ac-313b84841d04@oracle.com> List-Id: References: <1475796816-14448-1-git-send-email-tushar.n.dave@oracle.com> <1475796816-14448-7-git-send-email-tushar.n.dave@oracle.com> <20161007073252.GA8290@infradead.org> In-Reply-To: <20161007073252.GA8290@infradead.org> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: Christoph Hellwig Cc: davem@davemloft.net, chris.hyser@oracle.com, sowmini.varadhan@oracle.com, vgupta@synopsys.com, robin.murphy@arm.com, jroedel@suse.de, egtvedt@samfundet.no, krzk@kernel.org, sparclinux@vger.kernel.org, linux-kernel@vger.kernel.org On 10/07/2016 12:32 AM, Christoph Hellwig wrote: > On Thu, Oct 06, 2016 at 04:33:36PM -0700, Tushar Dave wrote: >> ATU 64bit addressing allows PCIe devices with 64bit DMA capabilities >> to use ATU for 64bit DMA. > > Any chance to always enable this? Last I checked sparc was the only > architecture still using a 32-bit dma_addr_t, leading to some fun > breakage in things like the software RDMA drivers that abuse it to > store a kernel pointer.. With change made by patch 6/6, dma_addr_t is always 64-bit, no matter if device DMA mask is 32-bit (i.e. using existing IOMMU) or 64-bit (i.e using ATU) -Tushar >