Questions about IOMMU & PCIe switch

[Raimonds Cicans <ray@apollo.lv>]

Hello.

We have two kinds of PCIe cards:
A1 - based on chip B
A2 - based on same chip B but behind PCIe switch

Card A1 work flawlessly in any configuration,
but card A2 work flawlessly only if system
lack IOMMU or have disabled IOMMU

Questions:
Do we have to treat card with PCIe switch in special way?
How?
Where (PCI bridge driver? card's driver?)?
Any examples in kernel?

Thank you.

Raimonds Cicans