Messages in this thread | | | Date | Thu, 29 Jan 2015 09:59:33 -0500 | From | Murali Karicheri <> | Subject | Re: [PATCH v4 1/6] of: iommu: add ptr to OF node arg to of_iommu_configure() |
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On 01/28/2015 06:32 PM, Laurent Pinchart wrote: > Hi Will, > > On Wednesday 28 January 2015 13:32:19 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<joro@8bytes.org> >>>>>>>>> Cc: Grant Likely<grant.likely@linaro.org> >>>>>>>>> Cc: Rob Herring<robh+dt@kernel.org> >>>>>>>>> Cc: Bjorn Helgaas<bhelgaas@google.com> >>>>>>>>> Cc: Will Deacon<will.deacon@arm.com> >>>>>>>>> Cc: Russell King<linux@arm.linux.org.uk> >>>>>>>>> Cc: Arnd Bergmann<arnd@arndb.de> >>>>>>>>> Cc: Suravee Suthikulpanit<Suravee.Suthikulpanit@amd.com> >>>>>>>>> >>>>>>>>> Signed-off-by: Murali Karicheri<m-karicheri2@ti.com> >>>>>>>>> --- >>>>>>>>> >>>>>>>>> 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. > > Indeed, that's right. I forgot for a moment that we have non-DT devices ;-) > > Acked-by: Laurent Pinchart<laurent.pinchart@ideasonboard.com> > > Murali, nitpicking a bit, shouldn't the iommu_np parameter be renamed ? It > points to the node containing the iommus parameter, not to the iommu node, so > the current name is slightly confusing. A brief kerneldoc above the function > would also help. This can be the subject of a separate patch. Probably the doc part can be added by Will. The iommu_np was a suggestion from Rob, if I recollect. Isn't the iommu_np points to the iommu device, and if so, iommu_np make sense.
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. >
-- Murali Karicheri Linux Kernel, Texas Instruments
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