From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-wi0-f182.google.com (mail-wi0-f182.google.com [209.85.212.182]) by kanga.kvack.org (Postfix) with ESMTP id BB8C56B0038 for ; Tue, 3 Feb 2015 09:37:31 -0500 (EST) Received: by mail-wi0-f182.google.com with SMTP id n3so22134168wiv.3 for ; Tue, 03 Feb 2015 06:37:31 -0800 (PST) Received: from pandora.arm.linux.org.uk (pandora.arm.linux.org.uk. [2001:4d48:ad52:3201:214:fdff:fe10:1be6]) by mx.google.com with ESMTPS id k10si43154770wjn.77.2015.02.03.06.37.28 for (version=TLSv1 cipher=RC4-SHA bits=128/128); Tue, 03 Feb 2015 06:37:28 -0800 (PST) Date: Tue, 3 Feb 2015 14:37:15 +0000 From: Russell King - ARM Linux Subject: Re: [RFCv3 2/2] dma-buf: add helpers for sharing attacher constraints with dma-parms Message-ID: <20150203143715.GQ8656@n2100.arm.linux.org.uk> References: <20150129143908.GA26493@n2100.arm.linux.org.uk> <20150129154718.GB26493@n2100.arm.linux.org.uk> <20150129192610.GE26493@n2100.arm.linux.org.uk> <20150202165405.GX14009@phenom.ffwll.local> <20150203074856.GF14009@phenom.ffwll.local> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Sender: owner-linux-mm@kvack.org List-ID: To: Rob Clark Cc: Sumit Semwal , LKML , "linux-media@vger.kernel.org" , DRI mailing list , Linaro MM SIG Mailman List , "linux-arm-kernel@lists.infradead.org" , "linux-mm@kvack.org" , Linaro Kernel Mailman List , Tomasz Stanislawski , Robin Murphy , Marek Szyprowski , Daniel Vetter On Tue, Feb 03, 2015 at 09:04:03AM -0500, Rob Clark wrote: > Since I'm stuck w/ an iommu, instead of built in mmu, my plan was to > drop use of dma-mapping entirely (incl the current call to dma_map_sg, > which I just need until we can use drm_cflush on arm), and > attach/detach iommu domains directly to implement context switches. > At that point, dma_addr_t really has no sensible meaning for me. So how do you intend to import from a subsystem which only gives you the dma_addr_t? If you aren't passing system memory, you have no struct page. You can't fake up a struct page. What this means is that struct scatterlist can't represent it any other way. -- FTTC broadband for 0.8mile line: currently at 10.5Mbps down 400kbps up according to speedtest.net. -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org