Re: [PATCH v3 2/5] iommu: Resolve fwspec ops automatically

[Will Deacon <will@kernel.org>]

On Fri, Jul 12, 2024 at 04:28:37PM +0100, Robin Murphy wrote:
> On 12/07/2024 4:24 pm, Jon Hunter wrote:
> > 
> > On 12/07/2024 12:48, Robin Murphy wrote:
> > 
> > ...
> > 
> > > > I am seeing some failures on -next with some of our devices.
> > > > Bisect is pointing to this commit. Looks like the host1x device
> > > > is no longer probing successfully. I see the following ...
> > > > 
> > > >   tegra-host1x 50000000.host1x: failed to initialize fwspec: -517
> > > >   nouveau 57000000.gpu: failed to initialize fwspec: -517
> > > > 
> > > > The probe seems to be deferred forever. The above is seen on
> > > > Tegra210 but Tegra30 and Tegra194 are also having the same
> > > > problem. Interestingly it is not all devices and so make me
> > > > wonder if we are missing something on these devices? Let me know
> > > > if you have any thoughts.
> > > 
> > > Ugh, tegra-smmu has been doing a complete nonsense this whole time -
> > > on closer inspection, it's passing the fwnode of the *client device*
> > > where it should be that of the IOMMU device :(
> > > 
> > > I *think* it should probably just be a case of:
> > > 
> > > -    err = iommu_fwspec_init(dev, of_fwnode_handle(dev->of_node));
> > > +    err = iommu_fwspec_init(dev, of_fwnode_handle(smmu->dev->of_node));
> > > 
> > > since smmu->dev appears to be the same one initially passed to
> > > iommu_device_register(), so it at least ought to match and work, but
> > > the SMMU device vs. MC device thing leaves me mildly wary of how
> > > correct it might be overall.
> > > 
> > > (Also now I'm wondering why I didn't just use dev_fwnode() there...)
> > 
> > 
> > Yes making that change in the tegra-smmu driver does fix it.
> 
> Ace, thanks for confirming! I was just writing a follow-up to say that I've
> pretty much convinced myself that this (proper diff below) should in fact be
> the right thing to do in general as well :)
> 
> Will, Joerg, would you prefer to have a standalone fix patch for the
> nvidia/tegra branch to then re-merge fwspec-ops-removal and fix up the
> conflict, or just a patch on top of fwspec-ops-removal as below?

I've just fixed it locally on the tegra branch, so I'll then just
resolve the conflict with fwspec-ops-removal the right way. That way, we
can backport the thing if we need to.

Cheers,

Will