From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932096AbbA3AYN (ORCPT ); Thu, 29 Jan 2015 19:24:13 -0500 Received: from galahad.ideasonboard.com ([185.26.127.97]:50815 "EHLO galahad.ideasonboard.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751534AbbA3AYL (ORCPT ); Thu, 29 Jan 2015 19:24:11 -0500 From: Laurent Pinchart To: Rob Herring Cc: Will Deacon , Murali Karicheri , "linux-arm-kernel@lists.infradead.org" , "linux-kernel@vger.kernel.org" , "linux-pci@vger.kernel.org" , "devicetree@vger.kernel.org" , "iommu@lists.linux-foundation.org" , Russell King , Arnd Bergmann , Joerg Roedel , Rob Herring , Bjorn Helgaas , "suravee.suthikulpanit@amd.com" , "grant.likely@linaro.org" Subject: Re: [PATCH v4 1/6] of: iommu: add ptr to OF node arg to of_iommu_configure() Date: Fri, 30 Jan 2015 02:24:51 +0200 Message-ID: <1612981.2C6LXFqAIA@avalon> User-Agent: KMail/4.14.3 (Linux/3.17.7-gentoo; KDE/4.14.3; x86_64; ; ) In-Reply-To: References: <1422052359-12384-1-git-send-email-m-karicheri2@ti.com> <5349994.6VHXzPdIxs@avalon> MIME-Version: 1.0 Content-Transfer-Encoding: 7Bit Content-Type: text/plain; charset="us-ascii" Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Rob, On Thursday 29 January 2015 10:49:38 Rob Herring wrote: > On Wed, Jan 28, 2015 at 5:32 PM, Laurent Pinchart wrote: > > On Wednesday 28 January 2015 13:32:19 Will Deacon wrote: > >> On Wed, Jan 28, 2015 at 01:15:10PM +0000, Laurent Pinchart wrote: > >>> On Wednesday 28 January 2015 12:29:42 Will Deacon wrote: > >>>> On Wed, Jan 28, 2015 at 12:23:03PM +0000, Laurent Pinchart wrote: > >>>>> On Wednesday 28 January 2015 11:33:00 Will Deacon wrote: > >>>>>> On Mon, Jan 26, 2015 at 06:49:01PM +0000, Murali Karicheri wrote: > >>>>>> On 01/25/2015 08:32 AM, Laurent Pinchart wrote: > >>>>>>>> On Friday 23 January 2015 17:32:34 Murali Karicheri wrote: > >>>>>>>>> Function of_iommu_configure() is called from of_dma_configure() > >>>>>>>>> to setup iommu ops using DT property. This API is currently used > >>>>>>>>> for platform devices for which DMA configuration (including iommu > >>>>>>>>> ops) may come from device's parent. To extend this functionality > >>>>>>>>> for PCI devices, this API need to take a parent node ptr as an > >>>>>>>>> argument instead of assuming device's parent. This is needed since > >>>>>>>>> for PCI, the dma configuration may be defined in the DT node of > >>>>>>>>> the root bus bridge's parent device. Currently only dma-range is > >>>>>>>>> used for PCI and iommu is not supported. So return error if the > >>>>>>>>> device is PCI. > > [...] > > >>> If I understand Murali's patch set right (please correct me if that's > >>> not the case) the PCI code walks up the DT nodes hierarchy to the > >>> parent node that contains the iommus attribute and passes a pointer to > >>> that node to this function. It's thus a PCI-specific solution. As a > >>> temporary hack that's OK I suppose, but if implementing it right > >>> straight away isn't difficult that would be better. > >> > >> It looks to me like the code walks the PCI topology to get the DT node > >> for the host controller, and passes *that* to of_dma_configure. That > >> sounds like the right thing to do to me, especially since the PCI > >> topology is likely not encoded in the device-tree. So actually, it is > >> passing the first parent node afaict. > > > > Indeed, that's right. I forgot for a moment that we have non-DT devices > > ;-) > > > > Acked-by: Laurent Pinchart > > > > Murali, nitpicking a bit, shouldn't the iommu_np parameter be renamed ? It > > points to the node containing the iommus parameter, not to the iommu node, > > so the current name is slightly confusing. A brief kerneldoc above the > > function would also help. This can be the subject of a separate patch. > > It was more confusing having np and node within the function. Agreed. How about master_np or iommu_master_np ? The latter might be a bit long. -- Regards, Laurent Pinchart