From mboxrd@z Thu Jan 1 00:00:00 1970 From: Murali Karicheri Subject: Re: [PATCH v4 1/6] of: iommu: add ptr to OF node arg to of_iommu_configure() Date: Fri, 30 Jan 2015 10:23:52 -0500 Message-ID: <54CBA208.5020005@ti.com> References: <1422052359-12384-1-git-send-email-m-karicheri2@ti.com> <5349994.6VHXzPdIxs@avalon> <1612981.2C6LXFqAIA@avalon> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii"; Format="flowed" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <1612981.2C6LXFqAIA@avalon> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: iommu-bounces-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org Errors-To: iommu-bounces-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org To: Laurent Pinchart Cc: "devicetree-u79uwXL29TY76Z2rM5mHXA@public.gmane.org" , Russell King , Arnd Bergmann , "linux-pci-u79uwXL29TY76Z2rM5mHXA@public.gmane.org" , Will Deacon , "linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org" , "grant.likely-QSEj5FYQhm4dnm+yROfE0A@public.gmane.org" , "iommu-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org" , Rob Herring , Rob Herring , Bjorn Helgaas , "linux-arm-kernel-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org" List-Id: devicetree@vger.kernel.org On 01/29/2015 07:24 PM, Laurent Pinchart wrote: > 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. > Probabaly master_np suffice as this function is named of_iommu_configure(). I will update it. -- Murali Karicheri Linux Kernel, Texas Instruments