From mboxrd@z Thu Jan 1 00:00:00 1970 From: Murali Karicheri Subject: Re: [PATCH v4 4/6] of/pci: add of_pci_dma_configure() update dma configuration Date: Tue, 27 Jan 2015 13:14:14 -0500 Message-ID: <54C7D576.6030502@ti.com> References: <1422052359-12384-1-git-send-email-m-karicheri2@ti.com> <1422052359-12384-5-git-send-email-m-karicheri2@ti.com> <20150123234124.GW29776@google.com> <54C6CCF3.7080308@ti.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii"; Format="flowed" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: 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: Bjorn Helgaas Cc: "devicetree-u79uwXL29TY76Z2rM5mHXA@public.gmane.org" , Russell King , Arnd Bergmann , "linux-pci-u79uwXL29TY76Z2rM5mHXA@public.gmane.org" , Will Deacon , "linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org" , "open list:INTEL IOMMU (VT-d)" , Rob Herring , Grant Likely , linux-arm List-Id: devicetree@vger.kernel.org On 01/26/2015 06:59 PM, Bjorn Helgaas wrote: > On Mon, Jan 26, 2015 at 5:25 PM, Murali Karicheri wrote: >> On 01/23/2015 06:41 PM, Bjorn Helgaas wrote: >>> >>> On Fri, Jan 23, 2015 at 05:32:37PM -0500, Murali Karicheri wrote: >>>> >>>> Add of_pci_dma_configure() to allow updating the dma configuration >>>> of the pci device using the configuration from DT of the parent of >>>> the root bridge device. >>>> -- Cut --- >>>> >>>> Signed-off-by: Murali Karicheri >>>> --- >>>> drivers/of/of_pci.c | 39 +++++++++++++++++++++++++++++++++++++++ >>>> include/linux/of_pci.h | 12 ++++++++++++ >>>> 2 files changed, 51 insertions(+) >>>> >>>> diff --git a/drivers/of/of_pci.c b/drivers/of/of_pci.c >>>> index 88471d3..34878c9 100644 >>>> --- a/drivers/of/of_pci.c >>>> +++ b/drivers/of/of_pci.c >>>> @@ -2,6 +2,7 @@ >>>> #include >>>> #include >>>> #include >>>> +#include >>>> #include >>>> #include >>>> >>>> @@ -229,6 +230,44 @@ parse_failed: >>>> return err; >>>> } >>>> EXPORT_SYMBOL_GPL(of_pci_get_host_bridge_resources); >>>> + >>>> +/** >>>> + * of_get_pci_root_bridge_parent - get the OF node of the root bridge's >>>> parent >>>> + * @dev: ptr to pci_dev struct of the pci device >>>> + * >>>> + * This function will traverse the bus up to the root bus starting with >>>> + * the child and return the OF node ptr to root bridge device's parent >>>> device. >>>> + */ >>>> +struct device_node *of_get_pci_root_bridge_parent(struct pci_dev *dev) >>> >>> >>> I'm not an OF person, but this interface seems like it might be too >>> special-purpose. Maybe it would be enough to add >>> "of_get_pci_root_bridge()", and the caller could do this: >>> >>> struct device *bridge = of_get_pci_root_bridge(dev); >>> struct device_node *parent_np = bridge->parent->of_node; >>> >>> Also, the name "of_get_..." suggests that it increments a refcount, as >>> of_get_parent() does. But you aren't doing anything with the refcount. >>> >>> But I guess an "of_get_pci_root_bridge()" isn't doing anything OF-related, >>> so maybe we should just add a "pci_get_host_bridge(struct pci_dev *)" >>> to PCI instead. >> >> >> Bjorn, >> >> Thanks for the comment. >> >> I think adding pci_get_host_bridge() is a good idea. There is already >> similar function in host-bridge.c. I have added this function re-using >> existing function find_pci_root_bus(). See the incremental diff below after >> this change. Does this look good? > > I like the implementation, but I think either we need to take a > reference on the host bridge, or change the name to something like > "pci_find_host_bridge()", because using "_get_" is conventional for > functions that acquire a reference. > > Since host bridges are hot-pluggable, at least in theory, I vote for > taking a reference. Then of course, you'd have to add code to drop > the reference when you're finished with it. > Bjorn, Thanks. I agree with your suggestion even though the convention is not followed fully :) of_pci_get_devfn(), of_get_pci_domain_nr(), of_pci_get_host_bridge_resources() are some of those functions not following the convention. I plan to change the function as below. Also want to name functions as pci_get/put_host_bridge_device() as existing function find_pci_host_bridge() is actually returning ptr to struct pci_host_bridge vs the new function returning ptr to device. Here are the new functions and how they will be used. Please review and respond so that I can avoid a re-spin. in linux/include/pci.h add the prototypes of pci_get/put_host_bridge_device(). in drivers/pci/host-bridge.c add two new functions. struct device *pci_get_host_bridge_device(struct pci_dev *dev) { struct pci_bus *root_bus = find_pci_root_bus(dev->bus); struct device *bridge = root_bus->bridge; kobject_get(&bridge->kobj); return bridge; } void pci_put_host_bridge_device(struct pci_dev *dev) { struct pci_bus *root_bus = find_pci_root_bus(dev->bus); struct device *bridge = root_bus->bridge; kobject_put(&bridge->kobj); } drivers/of/of_pci.c void of_pci_dma_configure(struct pci_dev *pci_dev) { struct device *dev = &pci_dev->dev; struct device *bridge = pci_get_host_bridge_device(pci_dev); of_dma_configure(dev, bridge->parent->of_node); pci_put_host_bridge_device(pci_dev); } Murali > Bjorn > >>>> >> >> >> -- >> Murali Karicheri >> Linux Kernel, Texas Instruments -- Murali Karicheri Linux Kernel, Texas Instruments