[kernel] powerpc/powernv/ioda2: Add devices only from buses which belong to PE

[Michael Ellerman]

On Fri, 2015-12-06 at 06:19:17 UTC, Alexey Kardashevskiy wrote:
> The existing code puts all devices from a root PE to the same IOMMU group.
> However it is a possible situation when subordinate buses belong to
> separate PEs, in this case devices from these subordinate buses
> should be added to lower level PE rather to the root PE.
> 
> This limits pnv_ioda_setup_bus_dma() invocation to only PEs which own
> all subordinate buses.
> 
> Suggested-by: Gavin Shan <gwshan at linux.vnet.ibm.com>
> Signed-off-by: Alexey Kardashevskiy <aik at ozlabs.ru>

Alexey/Gavin, can one of you write a better changelog for this. Explaining
what exactly is broken without it, how it fixes the problem, and why that is
the right fix.

cheers