From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from gate.crashing.org (gate.crashing.org [63.228.1.57]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (No client certificate requested) by lists.ozlabs.org (Postfix) with ESMTPS id 734341A084B for ; Fri, 3 Apr 2015 09:01:57 +1100 (AEDT) Message-ID: <1428012097.20500.279.camel@kernel.crashing.org> Subject: Re: [PATCH v8 RFC 1/3] sparc: Break up monolithic iommu table/lock into finer graularity pools and lock From: Benjamin Herrenschmidt To: Sowmini Varadhan Date: Fri, 03 Apr 2015 09:01:37 +1100 In-Reply-To: <1428011820.20500.277.camel@kernel.crashing.org> 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> Content-Type: text/plain; charset="UTF-8" Mime-Version: 1.0 Cc: aik@au1.ibm.com, anton@au1.ibm.com, paulus@samba.org, sparclinux@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, davem@davemloft.net List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , 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... Cheers, Ben.