From mboxrd@z Thu Jan 1 00:00:00 1970 From: Benjamin Herrenschmidt Date: Thu, 02 Apr 2015 22:02:59 +0000 Subject: Re: [PATCH v8 RFC 1/3] sparc: Break up monolithic iommu table/lock into finer graularity pools and l Message-Id: <1428012179.20500.280.camel@kernel.crashing.org> List-Id: References: <8406d119fb885255387a400551de994cb4a4c331.1427761300.git.sowmini.varadhan@oracle.com> <1428008044.20500.272.camel@kernel.crashing.org> <20150402214343.GA15680@oracle.com> <1428011820.20500.277.camel@kernel.crashing.org> <1428012097.20500.279.camel@kernel.crashing.org> In-Reply-To: <1428012097.20500.279.camel@kernel.crashing.org> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: Sowmini Varadhan Cc: aik@au1.ibm.com, anton@au1.ibm.com, paulus@samba.org, sparclinux@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, davem@davemloft.net On Fri, 2015-04-03 at 09:01 +1100, Benjamin Herrenschmidt wrote: > On Fri, 2015-04-03 at 08:57 +1100, Benjamin Herrenschmidt wrote: > > > No, the last argument to iommu_area_alloc() which is passed from the > > callers when doing consistent allocs. Basically, the DMA api mandates > > that consistent allocs are naturally aligned (to their own size), we > > implement that on powerpc by passing that alignment argument down. > > Talking of this ... I notice this is not documented in DMA-API.txt... > however many drivers make that assumption, and the DMA pool allocator > in mm/dmapool.c as well. > > Maybe somebody should update DMA-API.txt... Ah it *is* documented in DMA-API-HOWTO.txt :-) Cheers, Ben.