From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-ie0-f174.google.com (mail-ie0-f174.google.com [209.85.223.174]) by kanga.kvack.org (Postfix) with ESMTP id F37846B0038 for ; Tue, 3 Feb 2015 09:44:57 -0500 (EST) Received: by mail-ie0-f174.google.com with SMTP id vy18so25573617iec.5 for ; Tue, 03 Feb 2015 06:44:57 -0800 (PST) Received: from mail-ie0-x234.google.com (mail-ie0-x234.google.com. [2607:f8b0:4001:c03::234]) by mx.google.com with ESMTPS id g4si9846597igh.45.2015.02.03.06.44.57 for (version=TLSv1 cipher=ECDHE-RSA-RC4-SHA bits=128/128); Tue, 03 Feb 2015 06:44:57 -0800 (PST) Received: by mail-ie0-f180.google.com with SMTP id rl12so25565996iec.11 for ; Tue, 03 Feb 2015 06:44:57 -0800 (PST) MIME-Version: 1.0 In-Reply-To: <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> <20150203143715.GQ8656@n2100.arm.linux.org.uk> Date: Tue, 3 Feb 2015 09:44:57 -0500 Message-ID: Subject: Re: [RFCv3 2/2] dma-buf: add helpers for sharing attacher constraints with dma-parms From: Rob Clark Content-Type: text/plain; charset=UTF-8 Sender: owner-linux-mm@kvack.org List-ID: To: Russell King - ARM Linux 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 3, 2015 at 9:37 AM, Russell King - ARM Linux wrote: > 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. Tell the exporter to stop using carveouts, and give me proper memory instead.. ;-) Well, at least on these SoC's, I think the only valid use for carveout memory is the bootloader splashscreen. And I was planning on just hanging on to that for myself for fbdev scanout buffer or other internal (non shared) usage.. BR, -R > -- > 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