Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756120AbaGIOVe (ORCPT ); Wed, 9 Jul 2014 10:21:34 -0400 Received: from mail-we0-f178.google.com ([74.125.82.178]:63299 "EHLO mail-we0-f178.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754748AbaGIOVc (ORCPT ); Wed, 9 Jul 2014 10:21:32 -0400 Date: Wed, 9 Jul 2014 16:21:27 +0200 From: Thierry Reding To: Will Deacon Cc: Rob Herring , Pawel Moll , Mark Rutland , Ian Campbell , Kumar Gala , Stephen Warren , Arnd Bergmann , Joerg Roedel , Cho KyongHo , Grant Grundler , Dave P Martin , Marc Zyngier , Hiroshi Doyu , Olav Haugan , Varun Sethi , "devicetree@vger.kernel.org" , "iommu@lists.linux-foundation.org" , "linux-arm-kernel@lists.infradead.org" , "linux-tegra@vger.kernel.org" , "linux-kernel@vger.kernel.org" Subject: Re: [PATCH v4] devicetree: Add generic IOMMU device tree bindings Message-ID: <20140709142125.GB3262@ulmo> References: <1404487757-18829-1-git-send-email-thierry.reding@gmail.com> <20140709134050.GN9485@arm.com> MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="IrhDeMKUP4DT/M7F" Content-Disposition: inline In-Reply-To: <20140709134050.GN9485@arm.com> User-Agent: Mutt/1.5.23 (2014-03-12) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org --IrhDeMKUP4DT/M7F Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Wed, Jul 09, 2014 at 02:40:50PM +0100, Will Deacon wrote: > On Fri, Jul 04, 2014 at 04:29:17PM +0100, Thierry Reding wrote: > > From: Thierry Reding > >=20 > > This commit introduces a generic device tree binding for IOMMU devices. > > Only a very minimal subset is described here, but it is enough to cover > > the requirements of both the Exynos System MMU and Tegra SMMU as > > discussed here: > >=20 > > https://lkml.org/lkml/2014/4/27/346 > >=20 > > Signed-off-by: Thierry Reding >=20 > Acked-by: Will Deacon >=20 > I would like to move the ARM SMMU driver over to this for 3.18, if possib= le. > One use-case there is the ability to describe groups of masters behind a > multi-master IOMMU but which must be part of the same domain (i.e. an > iommu_group). This is useful for presenting devices to a guest with a > virtual SMMU, where the physical devices share a stage-2 context. >=20 > With your binding, does this simply mean determining the set of master IDs > in the group, then describing the complete set for each master? I'm not sure I properly understand what you're trying to do, but I don't think the binding is designed to cover that. Rather the goal was to describe the IDs belonging to each master, so that an IOMMU can be properly configured. Anything beyond that (e.g. logical grouping of masters) isn't directly within the scope of the binding (it doesn't describe hardware but some policy pertaining to some specific use-case). That said, the IOMMU driver that I prototyped for Tegra did some similar grouping of devices, although in a much more restricted way. The goal of that was to add a known set of devices into one group, "peripherals", so that they could share one IOMMU domain. This was meant to separate them =66rom devices with more advanced needs (such as a GPU driver). Devices in the "peripherals" group would be using the DMA mapping API integration whereas other devices would have to explicitly allocate an IOMMU domain. I'm not sure how much that helps for the use-case that you have in mind. Thierry --IrhDeMKUP4DT/M7F Content-Type: application/pgp-signature -----BEGIN PGP SIGNATURE----- Version: GnuPG v2 iQIcBAEBAgAGBQJTvU/lAAoJEN0jrNd/PrOhN50P/1dI3aJhI4/+i6WX1nsXpCN2 8VcmnlCJHdY1rmynJNk3WMEAepjVM6DRhDykwpPGRTD226yJWbiIfyIo53+yyx4a A4RjJKluaIfGL0bnlN/cg3lafoh3GwEkahTEPjhOHD8DgvYJNWu6ziojbaUplC9D V/UgfqHWtKrrxlum0nNJb8ObdJS/ef7RxAKLN08DMbZJe162Q+FNU/dMEQiueoJ8 +dGtEM27qP9+XMvgpeiqynyXTnc+/ZyTNQsrZuhwqHyhd3C0ey3aBQ0BF0Z2u4Yg ok//PUQcCYgL3mQaK0Ev2zlcHKwXIqt7HiSlIluzKXSPXvx/CUuEXaIjgzceWse8 9VZ1HmPnTW/UKlcvDdrG9GFtsXTZ9H4p/JGYbTsPM1+Ffc7wzwcKoXrqWigkd9iH KdYT3ZsYD/rqz2BrR+8twQJRgFqjku55vu4tojNNs0tt4s5u1RWqbF/9e/y8tPIb oM+tLOAsesyBcjlUeYogjT02XHh7SqWg8dSQFm+fMjmlbX6t4nuGCrJrVvSFBJtf BwRVX0bA1NM19ybK02GSeTgEOHyQUsQJ0tbkNF/RvYUvqEaXFShhDYZrLxSEk/j3 WoUhqKO48NvyWMlonaCwMM3DswiJX4raer6gbNUNXhSSSDIl+WQitkhqx81cKIQP bdnXlao7qtH18ZygWVGj =Hh+x -----END PGP SIGNATURE----- --IrhDeMKUP4DT/M7F-- -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/