Re: [PATCHv3 14/19] iommu/tegra: smmu: Get "nvidia,memory-clients" from DT

[Hiroshi Doyu <hdoyu-DDmLM1+adcrQT0dZR+AlfA@public.gmane.org>]

On Thu, 31 Oct 2013 20:39:41 +0100
Will Deacon <will.deacon-5wv7dgnIgG8@public.gmane.org> wrote:

> On Thu, Oct 31, 2013 at 07:25:25PM +0000, Stephen Warren wrote:
> > On 10/31/2013 01:16 PM, Stephen Warren wrote:
> > > Hmm. That's interesting. I see that the ARM SMMU has a list of the
> > > clients it affects, whereas this Tegra series puts information into each
> > > client device about the SMMU(s) that affect it. Is it better to flip the
> > > Tegra binding around to match the style of the ARM SMMU?
> > 
> > One question here: How do you ensure that the SMMU driver probe()s
> > before probe() runs for devices affected by the SMMU?
> 
> I think we get away with this by virtue of nobody actually creating IOMMU
> mappings from within drivers, so the ordering is already handled. However, I

Could you explain the above a bit more?

Currently I have a problem that IOMMU(tegra smmu) needs to be
instanciated earlier than other IOMMU'able devices since IOMMU needs
to configure devices IOMMU'ed at their instanciation time.

Now I'm considering to use iommu_bus_notifier or inserting a hook in
dd.c:really_probe() in order to defer a device instanciation til
IOMMU's instanciated.