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Date: Fri, 12 Jun 2015 08:06:43 -0700
From: Nishanth Aravamudan <nacc@linux.vnet.ibm.com>
To: Gavin Shan <gwshan@linux.vnet.ibm.com>
Cc: Alexey Kardashevskiy <aik@ozlabs.ru>, linux-kernel@vger.kernel.org,
 Paul Mackerras <paulus@samba.org>, linuxppc-dev@lists.ozlabs.org,
 David Gibson <david@gibson.dropbear.id.au>
Subject: Re: [PATCH kernel] powerpc/powernv/ioda2: Add devices only from
 buses which belong to PE
Message-ID: <20150612150643.GA55122@linux.vnet.ibm.com>
References: <1434089957-27135-1-git-send-email-aik@ozlabs.ru>
 <20150612064703.GA17776@gwshan>
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On 12.06.2015 [16:47:03 +1000], Gavin Shan wrote:
> On Fri, Jun 12, 2015 at 04:19:17PM +1000, 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@linux.vnet.ibm.com>
> >Signed-off-by: Alexey Kardashevskiy <aik@ozlabs.ru>
> 
> Alexey, I think it's good candidate for stable.

Why? This commit message doesn't imply there is a serious bug just a
"possible" (does that mean theoretical?) situtation and the following:

> >This would be nice to have together with the DDW patchset.
> >This does not fix anything DDW patchset did, it fixes IOMMU
> >groups management which is essential for the whole feature to work.

implies it is both related and independent of DDW?

-Nish