From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-ig0-f171.google.com (mail-ig0-f171.google.com [209.85.213.171]) by kanga.kvack.org (Postfix) with ESMTP id 9A9426B0070 for ; Tue, 3 Feb 2015 11:22:02 -0500 (EST) Received: by mail-ig0-f171.google.com with SMTP id h15so11508053igd.4 for ; Tue, 03 Feb 2015 08:22:02 -0800 (PST) Received: from mail-ie0-x229.google.com (mail-ie0-x229.google.com. [2607:f8b0:4001:c03::229]) by mx.google.com with ESMTPS id cy19si10004549igc.10.2015.02.03.08.22.02 for (version=TLSv1 cipher=ECDHE-RSA-RC4-SHA bits=128/128); Tue, 03 Feb 2015 08:22:02 -0800 (PST) Received: by mail-ie0-f169.google.com with SMTP id rl12so26362265iec.0 for ; Tue, 03 Feb 2015 08:22:02 -0800 (PST) MIME-Version: 1.0 In-Reply-To: <6906596.JU5vQoa1jV@wuerfel> References: <1422347154-15258-1-git-send-email-sumit.semwal@linaro.org> <3783167.LiVXgA35gN@wuerfel> <20150203155404.GV8656@n2100.arm.linux.org.uk> <6906596.JU5vQoa1jV@wuerfel> Date: Tue, 3 Feb 2015 11:22:01 -0500 Message-ID: Subject: Re: [Linaro-mm-sig] [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: Arnd Bergmann Cc: Russell King - ARM Linux , "linaro-mm-sig@lists.linaro.org" , Linaro Kernel Mailman List , Robin Murphy , LKML , DRI mailing list , "linux-mm@kvack.org" , Daniel Vetter , Tomasz Stanislawski , "linux-arm-kernel@lists.infradead.org" , "linux-media@vger.kernel.org" On Tue, Feb 3, 2015 at 11:12 AM, Arnd Bergmann wrote: > I agree for the case you are describing here. From what I understood > from Rob was that he is looking at something more like: > > Fig 3 > CPU--L1cache--L2cache--Memory--IOMMU-----device > > where the IOMMU controls one or more contexts per device, and is > shared across GPU and non-GPU devices. Here, we need to use the > dmap-mapping interface to set up the IO page table for any device > that is unable to address all of system RAM, and we can use it > for purposes like isolation of the devices. There are also cases > where using the IOMMU is not optional. Actually, just to clarify, the IOMMU instance is specific to the GPU.. not shared with other devices. Otherwise managing multiple contexts would go quite badly.. But other devices have their own instance of the same IOMMU.. so same driver could be used. BR, -R -- 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