From mboxrd@z Thu Jan 1 00:00:00 1970 From: Will Deacon Subject: Re: [PATCH v7 00/22] Generic DT bindings for PCI IOMMUs and ARM SMMU Date: Mon, 19 Sep 2016 13:24:36 +0100 Message-ID: <20160919122435.GD9005@arm.com> References: <11ebd81e-2ea5-5ff3-35b3-be95f03e05bd@redhat.com> <04a0a682-4fdc-8d62-57cd-efdf730582c6@redhat.com> <4d87d5f2-0350-b5f8-ffc3-4e9377cf1f87@redhat.com> <1838c65d-5944-8946-781c-b420bea1acab@redhat.com> <48f3bc10-3966-7d50-d070-7ec7f0946c92@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Content-Disposition: inline In-Reply-To: <48f3bc10-3966-7d50-d070-7ec7f0946c92-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org> Sender: devicetree-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: Auger Eric Cc: Robin Murphy , joro-zLv9SwRftAIdnm+yROfE0A@public.gmane.org, iommu-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org, linux-arm-kernel-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org, devicetree-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, punit.agrawal-5wv7dgnIgG8@public.gmane.org, thunder.leizhen-hv44wF8Li93QT0dZR+AlfA@public.gmane.org List-Id: devicetree@vger.kernel.org On Mon, Sep 19, 2016 at 02:13:45PM +0200, Auger Eric wrote: > On 16/09/2016 18:18, Robin Murphy wrote: > > What I probably will do, though, since we have the functionality in > > place for the sake of the old binding, and I think there are other folks > > who want PCI iommu-map support but would prefer not to bother with DMA > > ops on the host, is add a command-line option to disable DMA domains > > even for the generic bindings. > > Yes this would be a good thing I think. This series has an important > impact on platforms which do not have smmu v3, where contexts are scarce > HW resources. Rather than disabling DMA domains entirely, we could specify a number of contexts to reserve for other use (e.g. VFIO). It's a pity that these options are global for the system, as opposed to per SMMU instance, but I can't see a good way around that. Will -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo-u79uwXL29TY76Z2rM5mHXA@public.gmane.org More majordomo info at http://vger.kernel.org/majordomo-info.html From mboxrd@z Thu Jan 1 00:00:00 1970 From: will.deacon@arm.com (Will Deacon) Date: Mon, 19 Sep 2016 13:24:36 +0100 Subject: [PATCH v7 00/22] Generic DT bindings for PCI IOMMUs and ARM SMMU In-Reply-To: <48f3bc10-3966-7d50-d070-7ec7f0946c92@redhat.com> References: <11ebd81e-2ea5-5ff3-35b3-be95f03e05bd@redhat.com> <04a0a682-4fdc-8d62-57cd-efdf730582c6@redhat.com> <4d87d5f2-0350-b5f8-ffc3-4e9377cf1f87@redhat.com> <1838c65d-5944-8946-781c-b420bea1acab@redhat.com> <48f3bc10-3966-7d50-d070-7ec7f0946c92@redhat.com> Message-ID: <20160919122435.GD9005@arm.com> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org On Mon, Sep 19, 2016 at 02:13:45PM +0200, Auger Eric wrote: > On 16/09/2016 18:18, Robin Murphy wrote: > > What I probably will do, though, since we have the functionality in > > place for the sake of the old binding, and I think there are other folks > > who want PCI iommu-map support but would prefer not to bother with DMA > > ops on the host, is add a command-line option to disable DMA domains > > even for the generic bindings. > > Yes this would be a good thing I think. This series has an important > impact on platforms which do not have smmu v3, where contexts are scarce > HW resources. Rather than disabling DMA domains entirely, we could specify a number of contexts to reserve for other use (e.g. VFIO). It's a pity that these options are global for the system, as opposed to per SMMU instance, but I can't see a good way around that. Will