From mboxrd@z Thu Jan 1 00:00:00 1970 From: Joerg Roedel Subject: Re: [PATCH] iommu: Do not probe devices on IOMMU-less busses Date: Wed, 13 May 2020 10:42:50 +0200 Message-ID: <20200513084250.GC9820@8bytes.org> References: <20200511161000.3853342-1-thierry.reding@gmail.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Content-Disposition: inline In-Reply-To: <20200511161000.3853342-1-thierry.reding-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org> Sender: linux-tegra-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: Thierry Reding Cc: Jon Hunter , iommu-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org, linux-tegra-u79uwXL29TY76Z2rM5mHXA@public.gmane.org List-Id: linux-tegra@vger.kernel.org On Mon, May 11, 2020 at 06:10:00PM +0200, Thierry Reding wrote: > From: Thierry Reding > > The host1x bus implemented on Tegra SoCs is primarily an abstraction to > create logical device from multiple platform devices. Since the devices > in such a setup are typically hierarchical, DMA setup still needs to be > done so that DMA masks can be properly inherited, but we don't actually > want to attach the host1x logical devices to any IOMMU. The platform > devices that make up the logical device are responsible for memory bus > transactions, so it is them that will need to be attached to the IOMMU. > > Add a check to __iommu_probe_device() that aborts IOMMU setup early for > busses that don't have the IOMMU operations pointer set since they will > cause a crash otherwise. > > Signed-off-by: Thierry Reding > --- > Note that this is probably also required for the BCMA bus implemented in > drivers/bcma/main.c since no IOMMU operations are ever assigned to that > either. > > drivers/iommu/iommu.c | 3 +++ > 1 file changed, 3 insertions(+) Applied, thanks.