Re: [PATCH V4 1/3] driver core: mark device as irq affinity managed if any irq is managed

John Garry
2021-07-22T07:48:47Z

On 21/07/2021 21:22, Thomas Gleixner wrote:
>>> That's what I assumed, but this text from John suggested there is
>>> something odd about the platform case:
>>>
>>> "Did you consider that for PCI .."
>>> .
>> For this special platform MSI case there is a secondary interrupt
>> controller (called mbigen) which generates the MSI on behalf of the
>> device, which I think the MSI belongs to (and not the device, itself).
> MBIGEN is a different story because it converts wired interrupts into
> MSI interrupts, IOW a MSI based interrupt pin extender.
>
> I might be wrong, but I seriously doubt that any multiqueue device which
> wants to use affinity managed interrupts is built on top of that.

Actually the SCSI device for which platform device managed interrupts
support was added in commit e15f2fa959f2 uses mbigen.

Thanks,
John