From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752205AbbJXN2d (ORCPT ); Sat, 24 Oct 2015 09:28:33 -0400 Received: from v094114.home.net.pl ([79.96.170.134]:43884 "HELO v094114.home.net.pl" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with SMTP id S1750762AbbJXN2b (ORCPT ); Sat, 24 Oct 2015 09:28:31 -0400 From: "Rafael J. Wysocki" To: Tomeu Vizoso Cc: "linux-kernel@vger.kernel.org" , Rob Herring , Stephen Warren , Javier Martinez Canillas , Greg Kroah-Hartman , Mark Brown , Thierry Reding , Alan Stern , "linux-arm-kernel@lists.infradead.org" , Dmitry Torokhov , "devicetree@vger.kernel.org" , Linus Walleij , linux-acpi@vger.kernel.org, Arnd Bergmann Subject: Re: [PATCH v6 03/22] of/platform: Point to struct device from device node Date: Sat, 24 Oct 2015 15:57:24 +0200 Message-ID: <1806288.pmhamH8mKQ@vostro.rjw.lan> User-Agent: KMail/4.11.5 (Linux/4.1.0-rc5+; KDE/4.11.5; x86_64; ; ) In-Reply-To: References: <1442844182-27787-1-git-send-email-tomeu.vizoso@collabora.com> <1800338.r1NE3r6BDS@vostro.rjw.lan> MIME-Version: 1.0 Content-Transfer-Encoding: 7Bit Content-Type: text/plain; charset="utf-8" Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thursday, October 22, 2015 03:01:45 PM Tomeu Vizoso wrote: > On 22 October 2015 at 03:02, Rafael J. Wysocki wrote: > > On Monday, September 21, 2015 04:02:43 PM Tomeu Vizoso wrote: > >> When adding platform and AMBA devices, set the device node's device > >> member to point to it. > >> > >> This speeds lookups considerably and is safe because we only create one > >> of these devices for any given device node. > >> > >> Signed-off-by: Tomeu Vizoso > >> --- > >> > >> Changes in v5: > >> - Set the pointer to struct device also for AMBA devices > >> - Unset the pointer to struct device when the platform device is about > >> to be unregistered > >> - Increase the reference count of the device before returning from > >> of_find_device_by_node() > >> > >> drivers/of/platform.c | 19 ++++++++++--------- > >> include/linux/of.h | 1 + > >> 2 files changed, 11 insertions(+), 9 deletions(-) > >> > >> diff --git a/drivers/of/platform.c b/drivers/of/platform.c > >> index 1001efaedcb8..408d89f1d124 100644 > >> --- a/drivers/of/platform.c > >> +++ b/drivers/of/platform.c > >> @@ -32,11 +32,6 @@ const struct of_device_id of_default_bus_match_table[] = { > >> {} /* Empty terminated list */ > >> }; > >> > >> -static int of_dev_node_match(struct device *dev, void *data) > >> -{ > >> - return dev->of_node == data; > >> -} > >> - > >> /** > >> * of_find_device_by_node - Find the platform_device associated with a node > >> * @np: Pointer to device tree node > >> @@ -45,10 +40,10 @@ static int of_dev_node_match(struct device *dev, void *data) > >> */ > >> struct platform_device *of_find_device_by_node(struct device_node *np) > >> { > >> - struct device *dev; > >> - > >> - dev = bus_find_device(&platform_bus_type, NULL, np, of_dev_node_match); > >> - return dev ? to_platform_device(dev) : NULL; > >> + if (np->device && np->device->bus == &platform_bus_type && > >> + get_device(np->device)) > >> + return to_platform_device(np->device); > >> + return NULL; > >> } > >> EXPORT_SYMBOL(of_find_device_by_node); > >> > >> @@ -192,6 +187,8 @@ static struct platform_device *of_platform_device_create_pdata( > >> goto err_clear_flag; > >> } > >> > >> + np->device = &dev->dev; > >> + > >> return dev; > >> > >> err_clear_flag: > >> @@ -272,6 +269,8 @@ static struct amba_device *of_amba_device_create(struct device_node *node, > >> goto err_free; > >> } > >> > >> + node->device = &dev->dev; > >> + > >> return dev; > >> > >> err_free: > >> @@ -476,6 +475,8 @@ static int of_platform_device_destroy(struct device *dev, void *data) > >> if (of_node_check_flag(dev->of_node, OF_POPULATED_BUS)) > >> device_for_each_child(dev, NULL, of_platform_device_destroy); > >> > >> + dev->of_node->device = NULL; > >> + > >> if (dev->bus == &platform_bus_type) > >> platform_device_unregister(to_platform_device(dev)); > >> #ifdef CONFIG_ARM_AMBA > >> diff --git a/include/linux/of.h b/include/linux/of.h > >> index 2194b8ca41f9..eb091be0f8ee 100644 > >> --- a/include/linux/of.h > >> +++ b/include/linux/of.h > >> @@ -52,6 +52,7 @@ struct device_node { > >> phandle phandle; > >> const char *full_name; > >> struct fwnode_handle fwnode; > >> + struct device *device; > > > > There are cases in which multiple device objects point to the same device_node, > > so is the single struct device pointer here really sufficient? > > Only one struct device is registered for a given DT device node when > the DT is scanned (otherwise, of_find_device_by_node wouldn't be > safe). > > If some driver makes a struct device to point to a device_node that > already has a struct device associated with it, that's fine. Well, once that has happened, your new device pointer in the given device_node becomes useless. Why exactly is that fine? Thanks, Rafael