From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pd0-f176.google.com (mail-pd0-f176.google.com [209.85.192.176]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by lists.ozlabs.org (Postfix) with ESMTPS id B88511A08B0 for ; Sat, 13 Jun 2015 02:48:06 +1000 (AEST) Received: by pdjm12 with SMTP id m12so27874809pdj.3 for ; Fri, 12 Jun 2015 09:48:04 -0700 (PDT) Message-ID: <557B0D3C.6040100@ozlabs.ru> Date: Sat, 13 Jun 2015 02:47:56 +1000 From: Alexey Kardashevskiy MIME-Version: 1.0 To: Nishanth Aravamudan , Gavin Shan CC: linux-kernel@vger.kernel.org, Paul Mackerras , linuxppc-dev@lists.ozlabs.org, David Gibson Subject: Re: [PATCH kernel] powerpc/powernv/ioda2: Add devices only from buses which belong to PE References: <1434089957-27135-1-git-send-email-aik@ozlabs.ru> <20150612064703.GA17776@gwshan> <20150612150643.GA55122@linux.vnet.ibm.com> In-Reply-To: <20150612150643.GA55122@linux.vnet.ibm.com> Content-Type: text/plain; charset=koi8-r; format=flowed List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , On 06/13/2015 01:06 AM, Nishanth Aravamudan wrote: > 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 >>> Signed-off-by: Alexey Kardashevskiy >> >> 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? DDW is for fast devices and I just got my hands on a "firestone" machine (p8 + nvidia tesla = very fast machine) where this bug appeared first time. -- Alexey