From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-ob0-f170.google.com ([209.85.214.170]:57425 "EHLO mail-ob0-f170.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752980AbbAWWeh (ORCPT ); Fri, 23 Jan 2015 17:34:37 -0500 Received: by mail-ob0-f170.google.com with SMTP id wp4so72218obc.1 for ; Fri, 23 Jan 2015 14:34:36 -0800 (PST) Date: Fri, 23 Jan 2015 16:34:24 -0600 From: Bjorn Helgaas To: Lucas Stach Cc: Thierry Reding , linux-tegra@vger.kernel.org, linux-pci@vger.kernel.org Subject: Re: [PATCH v3 1/2] PCI: add helper function to find root port for device Message-ID: <20150123223424.GN29776@google.com> References: <1421179048-25370-1-git-send-email-l.stach@pengutronix.de> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii In-Reply-To: <1421179048-25370-1-git-send-email-l.stach@pengutronix.de> Sender: linux-pci-owner@vger.kernel.org List-ID: On Tue, Jan 13, 2015 at 08:57:27PM +0100, Lucas Stach wrote: > This adds a simple way to get the root port a given device > is connected to. > > Signed-off-by: Lucas Stach > --- > v2: new patch in v2 > v3: rename to pci_find_rootport to fit better with other API > --- > drivers/pci/search.c | 20 ++++++++++++++++++++ > include/linux/pci.h | 1 + > 2 files changed, 21 insertions(+) > > diff --git a/drivers/pci/search.c b/drivers/pci/search.c > index a20ce7d5e2a7..7254f126096d 100644 > --- a/drivers/pci/search.c > +++ b/drivers/pci/search.c > @@ -384,3 +384,23 @@ int pci_dev_present(const struct pci_device_id *ids) > return 0; > } > EXPORT_SYMBOL(pci_dev_present); > + > +/** > + * pci_find_root_port - Returns the root port the given device is connected to. > + * @dev: PCI device for which the root port should be found. > + */ > +struct pci_dev *pci_find_root_port(struct pci_dev *dev) This seems a little too generic. There are still PCI (non-PCIe) systems, and on those this will return some non-Root Port device, the meaning of which is unclear. I'm happy to put something like this in pci-tegra.c, but until there are other potential users and we sort out the PCI/PCIe-ness of the interface, I don't really want to make it global and exported. > +{ > + struct pci_bus *bus = dev->bus; > + > + /* If there is no bridge on the bus the passed device is a root port. */ This assumption is false -- see the comment at pci_is_root_bus(). > + if (!bus->self) > + return dev; > + > + /* Walk up the PCI hierarchy to the first level below the root. */ > + while (bus->parent && bus->parent->self) > + bus = bus->parent; > + > + return bus->self; > +} > +EXPORT_SYMBOL(pci_find_root_port); > diff --git a/include/linux/pci.h b/include/linux/pci.h > index 360a966a97a5..f4321c5ba653 100644 > --- a/include/linux/pci.h > +++ b/include/linux/pci.h > @@ -844,6 +844,7 @@ static inline struct pci_dev *pci_get_bus_and_slot(unsigned int bus, > } > struct pci_dev *pci_get_class(unsigned int class, struct pci_dev *from); > int pci_dev_present(const struct pci_device_id *ids); > +struct pci_dev *pci_find_root_port(struct pci_dev *dev); > > int pci_bus_read_config_byte(struct pci_bus *bus, unsigned int devfn, > int where, u8 *val); > -- > 2.1.4 >