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

[Robin Murphy]

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?

Thanks,
Robin.

----->8-----
diff --git a/drivers/iommu/tegra-smmu.c b/drivers/iommu/tegra-smmu.c
index 4365d9936e68..7f633bb5efef 100644
--- a/drivers/iommu/tegra-smmu.c
+++ b/drivers/iommu/tegra-smmu.c
@@ -837,7 +837,7 @@ static int tegra_smmu_configure(struct tegra_smmu 
*smmu, struct device *dev,
 	const struct iommu_ops *ops = smmu->iommu.ops;
 	int err;

-	err = iommu_fwspec_init(dev, of_fwnode_handle(dev->of_node));
+	err = iommu_fwspec_init(dev, dev_fwnode(smmu->dev));
 	if (err < 0) {
 		dev_err(dev, "failed to initialize fwspec: %d\n", err);
 		return err;