Re: [PATCH RFC v2 02/18] irq/dev-msi: Add support for a new DEV_MSI irq domain

From: Jason Gunthorpe
Date: Fri Aug 07 2020 - 14:39:35 EST

On Fri, Aug 07, 2020 at 10:54:51AM -0700, Dey, Megha wrote:

> So from the hierarchical domain standpoint, we will have:
> - For DSA device: vector->intel-IR->IDXD
> - For Jason's device: root domain-> domain A-> Jason's device's IRQ domain
> - For any other intel IMS device in the future which
>     does not require interrupt remapping: vector->new device IRQ domain
>     requires interrupt remapping: vector->intel-IR->new device IRQ domain

I think you need a better classification than Jason's device or
Intel's device :)

Shouldn't the two cases be either you take the parent domain from the
IOMMU or you take the parent domain from the pci device?

What other choices could a PCI driver make?