On Thu, Oct 01, 2020 at 11:33:38PM +0300, Dmitry Osipenko wrote: > >>> If we can't come to an agreement on globalizing mc pointer, would > >>> it be possible to pass tegra_mc_driver through tegra_smmu_probe() > >>> so we can continue to use driver_find_device_by_fwnode() as v1? > >>> > >>> v1: https://lkml.org/lkml/2020/9/26/68 > >> > >> tegra_smmu_probe() already takes a struct tegra_mc *. Did you mean > >> tegra_smmu_probe_device()? I don't think we can do that because it isn't > > > > I was saying to have a global parent_driver pointer: similar to > > my v1, yet rather than "extern" the tegra_mc_driver, we pass it > > through egra_smmu_probe() and store it in a static global value > > so as to call tegra_smmu_get_by_fwnode() in ->probe_device(). > > > > Though I agree that creating a global device pointer (mc) might > > be controversial, yet having a global parent_driver pointer may > > not be against the rule, considering that it is common in iommu > > drivers to call driver_find_device_by_fwnode in probe_device(). > > You don't need the global pointer if you have SMMU OF node. > > You could also get driver pointer from mc->dev->driver. > > But I don't think you need to do this at all. The probe_device() could > be invoked only for the tegra_smmu_ops and then seems you could use > dev_iommu_priv_set() in tegra_smmu_of_xlate(), like sun50i-iommu driver > does.
Getting iommu device pointer using driver_find_device_by_fwnode() is a common practice in ->probe_device() of other iommu drivers. But this requires a device_driver pointer that tegra-smmu doesn't have. So passing tegra_mc_driver through tegra_smmu_probe() will address it.
