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

Thomas Gleixner
2021-07-21T20:22:15Z

On Wed, Jul 21 2021 at 10:44, John Garry wrote:
> On 21/07/2021 08:24, Christoph Hellwig wrote:
>> On Wed, Jul 21, 2021 at 09:20:00AM +0200, Thomas Gleixner wrote:
>>>> Also does the above imply this won't work for your platform MSI case?
>>> The msi descriptors are attached to struct device and independent of
>>> platform/PCI/whatever.
>> 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.

Thanks,

tglx