From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751992AbbJCIUL (ORCPT ); Sat, 3 Oct 2015 04:20:11 -0400 Received: from bombadil.infradead.org ([198.137.202.9]:42622 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751410AbbJCIUH (ORCPT ); Sat, 3 Oct 2015 04:20:07 -0400 Date: Sat, 3 Oct 2015 01:19:52 -0700 From: Christoph Hellwig To: Benjamin Herrenschmidt Cc: Nishanth Aravamudan , Matthew Wilcox , Keith Busch , Paul Mackerras , Michael Ellerman , Alexey Kardashevskiy , David Gibson , Christoph Hellwig , linux-nvme@lists.infradead.org, linux-kernel@vger.kernel.org, linuxppc-dev@lists.ozlabs.org Subject: Re: [PATCH 0/5 v2] Fix NVMe driver support on Power with 32-bit DMA Message-ID: <20151003081952.GC24025@infradead.org> References: <20151002171606.GA41011@linux.vnet.ibm.com> <20151002200953.GB40695@linux.vnet.ibm.com> <1443819066.27295.19.camel@kernel.crashing.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1443819066.27295.19.camel@kernel.crashing.org> User-Agent: Mutt/1.5.23 (2014-03-12) X-SRS-Rewrite: SMTP reverse-path rewritten from by bombadil.infradead.org See http://www.infradead.org/rpr.html Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Sat, Oct 03, 2015 at 06:51:06AM +1000, Benjamin Herrenschmidt wrote: > On Fri, 2015-10-02 at 13:09 -0700, Nishanth Aravamudan wrote: > > > 1) add a generic dma_get_page_shift implementation that just returns > > PAGE_SHIFT > > So you chose to return the granularity of the iommu to the driver > rather than providing a way for the driver to request a specific > alignment for DMA mappings. Any specific reason ? At least for NVMe that's the way to go - it allows to set a page set in the device which should fit the IOMMU page size.