On Thu, Oct 01, 2020 at 12:56:46AM +0300, Dmitry Osipenko wrote: > 01.10.2020 00:32, Nicolin Chen пишет: > > On Thu, Oct 01, 2020 at 12:24:25AM +0300, Dmitry Osipenko wrote: > >> ... > >>>> It looks to me like the only reason why you need this new global API is > >>>> because PCI devices may not have a device tree node with a phandle to > >>>> the IOMMU. However, SMMU support for PCI will only be enabled if the > >>>> root complex has an iommus property, right? In that case, can't we > >>>> simply do something like this: > >>>> > >>>> if (dev_is_pci(dev)) > >>>> np = find_host_bridge(dev)->of_node; > >>>> else > >>>> np = dev->of_node; > >>>> > >>>> ? I'm not sure exactly what find_host_bridge() is called, but I'm pretty > >>>> sure that exists. > >>>> > >>>> Once we have that we can still iterate over the iommus property and do > >>>> not need to rely on this global variable. > >>> > >>> I agree that it'd work. But I was hoping to simplify the code > >>> here if it's possible. Looks like we have an argument on this > >>> so I will choose to go with your suggestion above for now. > >> > >> This patch removed more lines than were added. If this will be opposite > >> for the Thierry's suggestion, then it's probably not a great suggestion. > > > > Sorry, I don't quite understand this comments. Would you please > > elaborate what's this "it" being "not a great suggestion"? > > > > I meant that you should try to implement Thierry's solution, but if the > end result will be worse than the current patch, then you shouldn't make > a v4, but get back to this discussion in order to choose the best option > and make everyone agree on it.
I see. Thanks for the reply. And here is a sample implementation: @@ -814,12 +815,15 @@ static struct tegra_smmu *tegra_smmu_find(struct device_node *np) } static int tegra_smmu_configure(struct tegra_smmu *smmu, struct device *dev, - struct of_phandle_args *args) + struct of_phandle_args *args, struct fwnode_handle *fwnode) { const struct iommu_ops *ops = smmu->iommu.ops; int err; - err = iommu_fwspec_init(dev, &dev->of_node->fwnode, ops); + if (!fwnode) + return -ENOENT; + + err = iommu_fwspec_init(dev, fwnode, ops); if (err < 0) { dev_err(dev, "failed to initialize fwspec: %d\n", err); return err; @@ -835,6 +839,19 @@ static int tegra_smmu_configure(struct tegra_smmu *smmu, struct device *dev, return 0; } +static struct device_node *tegra_smmu_find_pci_np(struct pci_dev *pci_dev) +{ + struct pci_bus *bus = pci_dev->bus; + struct device *dev = &bus->dev; + + while (!of_property_read_bool(dev->of_node, "iommus") && bus->parent) { + dev = &bus->parent->dev; + bus = bus->parent; + } + + return dev->of_node; +} + static struct iommu_device *tegra_smmu_probe_device(struct device *dev) { struct device_node *np = dev->of_node; @@ -843,11 +860,14 @@ static struct iommu_device *tegra_smmu_probe_device(struct device *dev) unsigned int index = 0; int err; + if (dev_is_pci(dev)) + np = tegra_smmu_find_pci_np(to_pci_dev(dev)); + while (of_parse_phandle_with_args(np, "iommus", "#iommu-cells", index, &args) == 0) { smmu = tegra_smmu_find(args.np); if (smmu) { - err = tegra_smmu_configure(smmu, dev, &args); + err = tegra_smmu_configure(smmu, dev, &args, &np->fwnode); of_node_put(args.np); if (err < 0) _______________________________________________ iommu mailing list iommu@lists.linux-foundation.org https://lists.linuxfoundation.org/mailman/listinfo/iommu