From mboxrd@z Thu Jan 1 00:00:00 1970 From: Will Deacon Subject: Re: [PATCH v6 6/8] dma-mapping: detect and configure IOMMU in of_dma_configure Date: Wed, 7 Jan 2015 18:57:05 +0000 Message-ID: <20150107185704.GV7485@arm.com> References: <1417453034-21379-1-git-send-email-will.deacon@arm.com> <2983977.dWWQcFZRoJ@wuerfel> <20141221100451.GA23242@arm.com> <7693528.krAZff0s6I@wuerfel> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: Content-Disposition: inline In-Reply-To: <7693528.krAZff0s6I@wuerfel> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: iommu-bounces-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org Errors-To: iommu-bounces-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org To: Arnd Bergmann Cc: Joerg Roedel , "iommu-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org" , Thierry Reding , Laurent Pinchart , Varun Sethi , David Woodhouse , "linux-arm-kernel-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org" List-Id: iommu@lists.linux-foundation.org Hi Arnd, Sorry for the delay on this, I had to do a bit of digging. On Mon, Dec 22, 2014 at 01:36:01PM +0000, Arnd Bergmann wrote: > Do you think it's possible that we might have to deal with a single PCI host > that is connected two different SMMU instances for the purposes of extending > the StreamID space from 15 to 16 bits? I think we would have trouble > expressing this with the current syntax. Unfortunately, this sounds like something we may well have to support. Whilst the SMMUv2 architecture did grow a late extension to support 16-bit StreamIDs, that may have been too late for all silicon vendors and, as such, I'm not confident that such systems will present a single software interface for their SMMU. Will