Re: [RFC] PCI/MSI: Warning observed for NVMe with ACPI

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Hi Marc,

On 10/12/2021 11:39, Marc Zyngier wrote:

...

So the question is, should this be enabled by default for ARM64? I see
a lot of other architectures enabling this when PCI_MSI is enabled. So
I am wondering if we should be doing something like ...

diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig
index 1f212b47a48a..4bbd81bab809 100644
--- a/arch/arm64/Kconfig
+++ b/arch/arm64/Kconfig
@@ -202,6 +202,7 @@ config ARM64
         select PCI_DOMAINS_GENERIC if PCI
         select PCI_ECAM if (ACPI && PCI)
         select PCI_SYSCALL if PCI
+       select PCI_MSI_ARCH_FALLBACKS if PCI_MSI
         select POWER_RESET
         select POWER_SUPPLY
         select SPARSE_IRQ

+Thomas, as he's neck-deep in the MSI rework.

No, this definitely is the wrong solution.

arm64 doesn't need any arch fallback (I actually went out of my way to
kill them on this architecture), and requires the individual MSI
controller drivers to do the right thing by using MSI domains.  Adding
this config option makes the warning disappear, but the core issue is
that you have a device that doesn't have a MSI domain associated with
it.

So either your device isn't MSI capable (odd), your host bridge
doesn't make the link with the MSI controller to advertise the MSI
domain (this should normally be dealt with via IORT), or there is a
bug of a similar sort somewhere else.

Getting to the root of this issue would be the right thing to do.


Thanks! I will chat with Sagar about this and see what we are missing.

Jon

--
nvpublic



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