From mboxrd@z Thu Jan 1 00:00:00 1970 From: Murali Karicheri Subject: Re: [PATCH v4 1/6] of: iommu: add ptr to OF node arg to of_iommu_configure() Date: Wed, 28 Jan 2015 10:21:22 -0500 Message-ID: <54C8FE72.3060409@ti.com> References: <1422052359-12384-1-git-send-email-m-karicheri2@ti.com> <3953539.m9NpxSWcJ5@avalon> <20150128122941.GK1569@arm.com> <13812499.ICbNgSDOae@avalon> <20150128133219.GM1569@arm.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii"; Format="flowed" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <20150128133219.GM1569-5wv7dgnIgG8@public.gmane.org> 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: Will Deacon Cc: "devicetree-u79uwXL29TY76Z2rM5mHXA@public.gmane.org" , Russell King , Arnd Bergmann , "linux-pci-u79uwXL29TY76Z2rM5mHXA@public.gmane.org" , "linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org" , "grant.likely-QSEj5FYQhm4dnm+yROfE0A@public.gmane.org" , "iommu-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org" , Rob Herring , Laurent Pinchart , Bjorn Helgaas , "linux-arm-kernel-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org" List-Id: devicetree@vger.kernel.org On 01/28/2015 08:32 AM, Will Deacon wrote: > On Wed, Jan 28, 2015 at 01:15:10PM +0000, Laurent Pinchart wrote: >> On Wednesday 28 January 2015 12:29:42 Will Deacon wrote: >>> 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. >> >> If I understand Murali's patch set right (please correct me if that's not the >> case) the PCI code walks up the DT nodes hierarchy to the parent node that >> contains the iommus attribute and passes a pointer to that node to this >> function. It's thus a PCI-specific solution. As a temporary hack that's OK I >> suppose, but if implementing it right straight away isn't difficult that would >> be better. > > It looks to me like the code walks the PCI topology to get the DT node for > the host controller, and passes *that* to of_dma_configure. That sounds > like the right thing to do to me, especially since the PCI topology is > likely not encoded in the device-tree. So actually, it is passing the > first parent node afaict. > Laurent, Will, I don't have an IOMMU hardware to do more work on this. My patch series has been on this list for long and it is also increasing in scope :( I would suggest a follow up patch to this from someone (probably Will) and my patch goes as is with out further update. Hope this is reasonable. Murali > The part I'm more interested in is the mapping of RequesterID (PCI dma > alias) to IOMMU ID when we transition from the PCI topology to the DT > topology. Currently, it seems to be 1:1 on the platforms I have, but I > doubt this will always be the case. > > Will -- Murali Karicheri Linux Kernel, Texas Instruments