From patchwork Tue Aug 20 14:03:35 2013 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Mika Westerberg X-Patchwork-Id: 268540 Return-Path: X-Original-To: incoming@patchwork.ozlabs.org Delivered-To: patchwork-incoming@bilbo.ozlabs.org Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by ozlabs.org (Postfix) with ESMTP id 541C12C00E2 for ; Wed, 21 Aug 2013 00:04:01 +1000 (EST) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751497Ab3HTODn (ORCPT ); Tue, 20 Aug 2013 10:03:43 -0400 Received: from mga02.intel.com ([134.134.136.20]:16691 "EHLO mga02.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751249Ab3HTODl (ORCPT ); Tue, 20 Aug 2013 10:03:41 -0400 Received: from orsmga002.jf.intel.com ([10.7.209.21]) by orsmga101.jf.intel.com with ESMTP; 20 Aug 2013 07:03:40 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="4.89,920,1367996400"; d="scan'208";a="390245391" Received: from blue.fi.intel.com ([10.237.72.156]) by orsmga002.jf.intel.com with ESMTP; 20 Aug 2013 07:03:37 -0700 Received: by blue.fi.intel.com (Postfix, from userid 1004) id AA5E5E008E; Tue, 20 Aug 2013 17:03:36 +0300 (EEST) From: Mika Westerberg To: linux-i2c@vger.kernel.org Cc: Wolfram Sang , "Rafael J. Wysocki" , linux-acpi@vger.kernel.org, linux-kernel@vger.kernel.org, Lv Zheng , Aaron Lu , Mika Westerberg Subject: [RFC PATCH 1/2] i2c: prepare runtime PM support for I2C client devices Date: Tue, 20 Aug 2013 17:03:35 +0300 Message-Id: <1377007416-13851-2-git-send-email-mika.westerberg@linux.intel.com> X-Mailer: git-send-email 1.8.4.rc2 In-Reply-To: <1377007416-13851-1-git-send-email-mika.westerberg@linux.intel.com> References: <1377007416-13851-1-git-send-email-mika.westerberg@linux.intel.com> Sender: linux-i2c-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-i2c@vger.kernel.org From: Aaron Lu This patch adds runtime PM support for the I2C bus in a similar way that has been done for PCI bus already. This means that the I2C bus core prepares runtime PM for a client device just before a driver is about to be bound to it. Devices that are not bound to any driver are not prepared for runtime PM. In order to take advantage of this runtime PM support, the client device driver needs drop the device runtime PM reference count by calling pm_runtime_put() in its ->probe() callback and possibly implement rest of the runtime PM callbacks. However, this does not yet make runtime PM happen for the device, it has to be explicitly allowed from userspace per each I2C client device. The reason for this is that things like HID over I2C might not work as smoothly when runtime PM is active. So we leave it to the user to balance between performance and power efficiency. User can allow runtime PM for the client device by running: # echo auto > /sys/bus/i2c/devices//power/control and it can be forbidden again by: # echo on > /sys/bus/i2c/devices//power/control Status of the device can be monitored by reading files under the device power directory. If the driver doesn't support runtime PM (like most of the existing I2C client drivers), the device in question is regarded as being runtime PM active and powered on. The patch adds also runtime PM support for the adapter device because it is needed to be able to runtime power manage the I2C controller device. The adapter device is handled along with the I2C controller device (it uses pm_runtime_no_callbacks()). Signed-off-by: Aaron Lu Signed-off-by: Mika Westerberg Acked-by: Rafael J. Wysocki --- drivers/i2c/i2c-core.c | 48 +++++++++++++++++++++++++++++++++++++++++++++++- 1 file changed, 47 insertions(+), 1 deletion(-) diff --git a/drivers/i2c/i2c-core.c b/drivers/i2c/i2c-core.c index 3d44292..8fad5ac 100644 --- a/drivers/i2c/i2c-core.c +++ b/drivers/i2c/i2c-core.c @@ -254,11 +254,34 @@ static int i2c_device_probe(struct device *dev) client->flags & I2C_CLIENT_WAKE); dev_dbg(dev, "probe\n"); + /* Make sure the adapter is active */ + pm_runtime_get_sync(&client->adapter->dev); + + /* + * Enable runtime PM for the client device. If the client wants to + * participate on runtime PM it should call pm_runtime_put() in its + * probe() callback. + * + * User still needs to allow the PM runtime before it can actually + * happen. + */ + pm_runtime_forbid(&client->dev); + pm_runtime_get_noresume(&client->dev); + pm_runtime_set_active(&client->dev); + pm_runtime_enable(&client->dev); + status = driver->probe(client, i2c_match_id(driver->id_table, client)); if (status) { client->driver = NULL; i2c_set_clientdata(client, NULL); + + pm_runtime_disable(&client->dev); + pm_runtime_set_suspended(&client->dev); + pm_runtime_put_noidle(&client->dev); } + + pm_runtime_put(&client->adapter->dev); + return status; } @@ -271,6 +294,8 @@ static int i2c_device_remove(struct device *dev) if (!client || !dev->driver) return 0; + pm_runtime_get_sync(&client->adapter->dev); + driver = to_i2c_driver(dev->driver); if (driver->remove) { dev_dbg(dev, "remove\n"); @@ -283,6 +308,13 @@ static int i2c_device_remove(struct device *dev) client->driver = NULL; i2c_set_clientdata(client, NULL); } + + /* Undo the runtime PM done in i2c_probe() */ + pm_runtime_disable(&client->dev); + pm_runtime_set_suspended(&client->dev); + pm_runtime_put_noidle(&client->dev); + + pm_runtime_put(&client->adapter->dev); return status; } @@ -294,8 +326,11 @@ static void i2c_device_shutdown(struct device *dev) if (!client || !dev->driver) return; driver = to_i2c_driver(dev->driver); - if (driver->shutdown) + if (driver->shutdown) { + pm_runtime_get_sync(&client->adapter->dev); driver->shutdown(client); + pm_runtime_put(&client->adapter->dev); + } } #ifdef CONFIG_PM_SLEEP @@ -1263,6 +1298,15 @@ exit_recovery: bus_for_each_drv(&i2c_bus_type, NULL, adap, __process_new_adapter); mutex_unlock(&core_lock); + /* + * Make sure the adapter runtime PM follows the parent device (the + * host controller) so that we can suspend it once there aren't any + * active clients anymore. + */ + pm_runtime_set_active(&adap->dev); + pm_runtime_no_callbacks(&adap->dev); + pm_runtime_enable(&adap->dev); + return 0; out_list: @@ -1427,6 +1471,8 @@ void i2c_del_adapter(struct i2c_adapter *adap) return; } + pm_runtime_disable(&adap->dev); + /* Tell drivers about this removal */ mutex_lock(&core_lock); bus_for_each_drv(&i2c_bus_type, NULL, adap,