From mboxrd@z Thu Jan 1 00:00:00 1970 From: Will Deacon Subject: Re: [PATCH v4 1/6] of: iommu: add ptr to OF node arg to of_iommu_configure() Date: Wed, 28 Jan 2015 12:29:42 +0000 Message-ID: <20150128122941.GK1569@arm.com> References: <1422052359-12384-1-git-send-email-m-karicheri2@ti.com> <54C68C1D.5030605@ti.com> <20150128113300.GF1569@arm.com> <3953539.m9NpxSWcJ5@avalon> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: Content-Disposition: inline In-Reply-To: <3953539.m9NpxSWcJ5@avalon> 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: Laurent Pinchart Cc: "devicetree-u79uwXL29TY76Z2rM5mHXA@public.gmane.org" , Russell King , Arnd Bergmann , "linux-pci-u79uwXL29TY76Z2rM5mHXA@public.gmane.org" , "linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org" , Rob Herring , "grant.likely-QSEj5FYQhm4dnm+yROfE0A@public.gmane.org" , "iommu-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org" , Murali Karicheri , Bjorn Helgaas , "linux-arm-kernel-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org" List-Id: devicetree@vger.kernel.org On Wed, Jan 28, 2015 at 12:23:03PM +0000, Laurent Pinchart wrote: > On Wednesday 28 January 2015 11:33:00 Will Deacon wrote: > > On Mon, Jan 26, 2015 at 06:49:01PM +0000, Murali Karicheri wrote: > > > On 01/25/2015 08:32 AM, Laurent Pinchart wrote: > > >> On Friday 23 January 2015 17:32:34 Murali Karicheri wrote: > > >>> Function of_iommu_configure() is called from of_dma_configure() to > > >>> setup iommu ops using DT property. This API is currently used for > > >>> platform devices for which DMA configuration (including iommu ops) > > >>> may come from device's parent. To extend this functionality for PCI > > >>> devices, this API need to take a parent node ptr as an argument > > >>> instead of assuming device's parent. This is needed since for PCI, the > > >>> dma configuration may be defined in the DT node of the root bus > > >>> bridge's parent device. Currently only dma-range is used for PCI and > > >>> iommu is not supported. So return error if the device is PCI. > > >>> > > >>> Cc: Joerg Roedel > > >>> Cc: Grant Likely > > >>> Cc: Rob Herring > > >>> Cc: Bjorn Helgaas > > >>> Cc: Will Deacon > > >>> Cc: Russell King > > >>> Cc: Arnd Bergmann > > >>> Cc: Suravee Suthikulpanit > > >>> > > >>> Signed-off-by: Murali Karicheri > > >>> --- > > >>> > > >>> drivers/iommu/of_iommu.c | 10 ++++++++-- > > >>> drivers/of/platform.c | 2 +- > > >>> include/linux/of_iommu.h | 6 ++++-- > > >>> 3 files changed, 13 insertions(+), 5 deletions(-) > > >>> > > >>> diff --git a/drivers/iommu/of_iommu.c b/drivers/iommu/of_iommu.c > > >>> index af1dc6a..439235b 100644 > > >>> --- a/drivers/iommu/of_iommu.c > > >>> +++ b/drivers/iommu/of_iommu.c > > >>> @@ -133,19 +133,25 @@ struct iommu_ops *of_iommu_get_ops(struct > > >>> device_node *np) > > >>> return ops; > > >>> } > > >>> > > >>> -struct iommu_ops *of_iommu_configure(struct device *dev) > > >>> +struct iommu_ops *of_iommu_configure(struct device *dev, > > >>> + struct device_node *iommu_np) > > >>> { > > >>> struct of_phandle_args iommu_spec; > > >>> struct device_node *np; > > >>> struct iommu_ops *ops = NULL; > > >>> int idx = 0; > > >>> > > >>> + if (dev_is_pci(dev)) { > > >>> + dev_err(dev, "iommu is currently not supported for PCI\n"); > > >>> + return NULL; > > >>> + } > > >>> + > > >>> /* > > >>> * We don't currently walk up the tree looking for a parent IOMMU. > > >>> * See the `Notes:' section of > > >>> * Documentation/devicetree/bindings/iommu/iommu.txt > > >>> */ > > >> > > >> Wouldn't it be better to fix this rather than passing the device node > > >> pointer to the function ? The solution would be more generic. > > > > > > Will Deacon (Copied here) is working on this as we alteady discussed in > > > this thread. So it will be addressed by him in another series. > > > > Well, "working on this" equates to "has it somewhere near the bottom of > > a very long list" :) > > What's your opinion on this patch then, do you think adding the iommu_np > argument makes sense as a temporary hack, or should we instead walk up the > tree looking for an iommus attribute in parent nodes ? I don't expect that to > be insanely difficult to code. If walking up the tree is useful, then I think we should do that and update the Documentation to reflect the new behaviour. The only reason that I didn't code that in of_iommu_configure originally is because I didn't want to go against the binding spec for the initial version, especially as we didn't have a reason to look at parent nodes. The only thing to double-check is that we don't break any existing users of the binding with this change, but I don't think that we do. Will