Re: [PATCH v3 2/3] iommu/tegra-smmu: Rework .probe_device and .attach_dev

[Dmitry Osipenko]

 I'...
>> +	struct tegra_mc *mc = devm_tegra_get_memory_controller(dev);
>> +	struct iommu_fwspec *fwspec = dev_iommu_fwspec_get(dev);
> 
> 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.

This sounds more complicated than the current variant.

Secondly, I'm already about to use the new tegra_get_memory_controller()
API for all the T20/30/124/210 EMC and devfreq drivers.