Message-ID: <fe8c2233-fa2a-4356-8005-6cbabf6a0e96@socionext.com>
Date: Fri, 31 Jan 2025 19:16:54 +0900
From: Kunihiko Hayashi <hayashi.kunihiko@...ionext.com>
To: Niklas Cassel <cassel@...nel.org>,
 Manivannan Sadhasivam <manivannan.sadhasivam@...aro.org>
Cc: Krzysztof Wilczyński <kw@...ux.com>,
 Kishon Vijay Abraham I <kishon@...nel.org>, Arnd Bergmann <arnd@...db.de>,
 Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
 Lorenzo Pieralisi <lpieralisi@...nel.org>,
 Gustavo Pimentel <gustavo.pimentel@...opsys.com>,
 Bjorn Helgaas <helgaas@...nel.org>, linux-pci@...r.kernel.org,
 linux-kernel@...r.kernel.org, stable@...r.kernel.org
Subject: Re: [PATCH v2 3/3] misc: pci_endpoint_test: Fix irq_type to convey
 the correct type

Hi Niklas,

On 2025/01/29 20:58, Niklas Cassel wrote:
> On Tue, Jan 28, 2025 at 08:02:31PM +0530, Manivannan Sadhasivam wrote:
>> On Wed, Jan 22, 2025 at 11:24:46AM +0900, Kunihiko Hayashi wrote:
>>> There are two variables that indicate the interrupt type to be used
>>> in the next test execution, "irq_type" as global and test->irq_type.
>>>
>>> The global is referenced from pci_endpoint_test_get_irq() to preserve
>>> the current type for ioctl(PCITEST_GET_IRQTYPE).
>>>
>>> The type set in this function isn't reflected in the global "irq_type",
>>> so ioctl(PCITEST_GET_IRQTYPE) returns the previous type.
>>> As a result, the wrong type will be displayed in "pcitest" as follows:
>>>
>>>      # pcitest -i 0
>>>      SET IRQ TYPE TO LEGACY:         OKAY
>>>      # pcitest -I
>>>      GET IRQ TYPE:           MSI
>>>
>>> Fix this issue by propagating the current type to the global "irq_type".
>>>
>>
>> This is becoming a nuisance. I think we should get rid of the global
>> 'irq_type'
>> and just stick to the one that is configurable using IOCTL command. Even
>> if the
>> user has configured the global 'irq_type' it is bound to change with IOCTL
>> command.
> 
> +1

After fixing the issue described in this patch,
we can replace with a new member of 'struct pci_endpoint_test' instead.

> But I also don't like how since we migrated to selftests:
> READ_TEST / WRITE_TEST / COPY_TEST unconditionally call
> ioctl(PCITEST_SET_IRQTYPE, MSI) before doing their thing.

I think that it's better to prepare new patch series.

> Will this cause the test case to fail for platforms that only support MSI-X?
> (See e.g. dwc/pci-layerscape-ep.c where this could be the case.)
> 
> 
> Sure, before, in pcitest.sh, we would do:
> 
> 
> pcitest -i 2
>          pcitest -x $msix
> 
> 
> pcitest -i 1
> 
> pcitest -r -s 1
> pcitest -r -s 1024
> pcitest -r -s 1025
> pcitest -r -s 1024000
> pcitest -r -s 1024001
> 
> 
> Which would probably print an error if:
> pcitest -i 1
> failed.
> 
> but the READ_TEST / WRITE_TEST / COPY_TEST tests themselves
> would not fail.
> 
> 
> Perhaps we should rethink this, and introduce a new
> PCITEST_SET_IRQTYPE, AUTO
> 
> I would be fine if
> READ_TEST / WRITE_TEST / COPY_TEST
> called PCITEST_SET_IRQTYPE, AUTO
> before doing their thing.
> 
> 
> 
> How I suggest PCITEST_SET_IRQTYPE, AUTO
> would work:
> 
> Since we now have capabilties merged:
> https://lore.kernel.org/linux-pci/20241203063851.695733-4-cassel@kernel.org/
> 
> Add epc_features->msi_capable and epc->features->msix_capable
> as two new bits in the PCI_ENDPOINT_TEST_CAPS register.
> 
> If PCITEST_SET_IRQTYPE, AUTO:
> if EP CAP has msi_capable set: set IRQ type MSI
> else if EP CAP has msix_capable set: set IRQ type MSI-X
> else: set legacy/INTx

There is something ambiguous about the behavior for me.

The test->irq_type has a state "UNDEFINED".
After issueing "Clear IRQ", test->irq_type becomes "UNDEFINED" currently,
and all tests with IRQs will fail until new test->irq_type is set.

If SET_IRQTYPE is AUTO, how will test->irq_type be set?

Thank you,

---
Best Regards
Kunihiko Hayashi

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