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

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Message-ID: <20240712153137.GC16474@willie-the-truck>
Date: Fri, 12 Jul 2024 16:31:38 +0100
From: Will Deacon <will@...nel.org>
To: Robin Murphy <robin.murphy@....com>
Cc: Jon Hunter <jonathanh@...dia.com>, Joerg Roedel <joro@...tes.org>,
	linux-acpi@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
	linux-kernel@...r.kernel.org, iommu@...ts.linux.dev,
	devicetree@...r.kernel.org, Rob Herring <robh@...nel.org>,
	Saravana Kannan <saravanak@...gle.com>,
	Lorenzo Pieralisi <lpieralisi@...nel.org>,
	Hanjun Guo <guohanjun@...wei.com>,
	Sudeep Holla <sudeep.holla@....com>,
	"Rafael J. Wysocki" <rafael@...nel.org>,
	Len Brown <lenb@...nel.org>,
	Jean-Philippe Brucker <jean-philippe@...aro.org>,
	Andy Shevchenko <andy.shevchenko@...il.com>,
	Yong Wu <yong.wu@...iatek.com>,
	"linux-tegra@...r.kernel.org" <linux-tegra@...r.kernel.org>
Subject: Re: [PATCH v3 2/5] iommu: Resolve fwspec ops automatically

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