From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753014AbbE0RiN (ORCPT ); Wed, 27 May 2015 13:38:13 -0400 Received: from foss.arm.com ([217.140.101.70]:53006 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751586AbbE0RiL (ORCPT ); Wed, 27 May 2015 13:38:11 -0400 Date: Wed, 27 May 2015 18:38:06 +0100 From: Will Deacon To: Laurent Pinchart Cc: "linux-kernel@vger.kernel.org" , "linux-arm-kernel@lists.infradead.org" , "iommu@lists.linux-foundation.org" , Laura Abbott , Arnd Bergmann , Mitchel Humpherys , Joreg Roedel , "grant.likely@linaro.org" , Robin Murphy , Marek Szyprowski , Thierry Reding , Greg Kroah-Hartman Subject: Re: [RFC/PATCH 1/9] arm: dma-mapping: Don't override dma_ops in arch_setup_dma_ops() Message-ID: <20150527173806.GD4232@arm.com> References: <1431644410-2997-1-git-send-email-laurent.pinchart+renesas@ideasonboard.com> <1431644410-2997-2-git-send-email-laurent.pinchart+renesas@ideasonboard.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1431644410-2997-2-git-send-email-laurent.pinchart+renesas@ideasonboard.com> User-Agent: Mutt/1.5.23 (2014-03-12) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, May 15, 2015 at 12:00:02AM +0100, Laurent Pinchart wrote: > The arch_setup_dma_ops() function is in charge of setting dma_ops with a > call to set_dma_ops(). set_dma_ops() is also called from > > - highbank and mvebu bus notifiers > - dmabounce (to be replaced with swiotlb) > - arm_iommu_attach_device > > (arm_iommu_attach_device is itself called from IOMMU and bus master > device drivers) > > To allow the arch_setup_dma_ops() call to be moved from device add time > to device probe time we must ensure that dma_ops already setup by any of > the above callers will not be overriden. > > Aftering replacing dmabounce with swiotlb, converting IOMMU drivers to s/Aftering/After/ > of_xlate and taking care of highbank and mvebu, the workaround should be > removed. > > Signed-off-by: Laurent Pinchart > --- > arch/arm/mm/dma-mapping.c | 9 +++++++++ > 1 file changed, 9 insertions(+) > > diff --git a/arch/arm/mm/dma-mapping.c b/arch/arm/mm/dma-mapping.c > index 09c5fe3d30c2..7aa5e339a596 100644 > --- a/arch/arm/mm/dma-mapping.c > +++ b/arch/arm/mm/dma-mapping.c > @@ -2117,6 +2117,15 @@ void arch_setup_dma_ops(struct device *dev, u64 dma_base, u64 size, > struct dma_map_ops *dma_ops; > > dev->archdata.dma_coherent = coherent; > + > + /* > + * Don't override the dma_ops if they have already been set. Ideally > + * this should be the only location where dma_ops are set, remove this > + * check when all other callers of set_dma_ops will have disappeared. > + */ > + if (dev->archdata.dma_ops) > + return; Maybe printing a warning at the same time will encourage people to migrate away from the existing behaviour? Will