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

[Jon Hunter <jonathanh@nvidia.com>]

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