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

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Message-ID: <96c1f2ff-7cb6-42bb-92fc-ab64ba8c1060@arm.com>
Date: Fri, 12 Jul 2024 16:34:11 +0100
From: Robin Murphy <robin.murphy@....com>
To: Will Deacon <will@...nel.org>
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 12/07/2024 4:31 pm, Will Deacon wrote:
> 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 ...
>>>>>
>>>>> ï¿½ï¿½tegra-host1x 50000000.host1x: failed to initialize fwspec: -517
>>>>> ï¿½ï¿½nouveau 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:
>>>>
>>>> -ï¿½ï¿½ï¿½ err = iommu_fwspec_init(dev, of_fwnode_handle(dev->of_node));
>>>> +ï¿½ï¿½ï¿½ 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.

Cool, thanks for taking care of it!

Robin.