From patchwork Thu Sep 29 14:46:17 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Patchwork-Submitter: =?utf-8?q?M=C3=A5rten_Lindahl?= X-Patchwork-Id: 611311 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id B0989C4321E for ; Thu, 29 Sep 2022 14:46:39 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S235303AbiI2Oqh (ORCPT ); Thu, 29 Sep 2022 10:46:37 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:57606 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S235223AbiI2Oqd (ORCPT ); Thu, 29 Sep 2022 10:46:33 -0400 Received: from smtp2.axis.com (smtp2.axis.com [195.60.68.18]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 16FA9137464; Thu, 29 Sep 2022 07:46:26 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=axis.com; q=dns/txt; s=axis-central1; t=1664462790; x=1695998790; h=from:to:cc:subject:date:message-id:in-reply-to: references:mime-version:content-transfer-encoding; bh=CFsrUS0Wazhhw4e5WndLnkA03gM+PhS0QY5XoDf9+Ss=; b=BZevCYjIxUuu3VB7FAMp7cDf7Cc7tN4OuVcw6sZAMsee+1//nU7rUFOx 3iHzH52Flkn2hOQxX8QvMEvxs5P4/McOZBvMFGkxxi+Ves5skOnrfUnao 4rN1nSsy0J5fmM8Lw6zipaPnZag/+rMI5kc1ezsZLVRjziSs4Tv3kOIjM CbZC98WT+A6nhX3ljvQ7At3bYvWDQxraPO2H6iQmlwviMSX1Ytqrz241A gSwpPb/a5tnhPWX/48kqvxwYyy+v8izQBjut3d/IM0YXBEZFvwNBvj0AZ ddvJWNI8rEWKHse+xwAvfW34ANa6MFf0BSixrKcJ2GKJQHxnsN5zINVo5 w==; From: =?utf-8?q?M=C3=A5rten_Lindahl?= To: "Rafael J. Wysocki" , Pavel Machek , Jonathan Cameron CC: Lars-Peter Clausen , Greg Kroah-Hartman , , , , =?utf-8?q?M=C3=A5rten_Linda?= =?utf-8?q?hl?= Subject: [PATCH 1/2] PM: runtime: Synchronize PM runtime enable state with parent Date: Thu, 29 Sep 2022 16:46:17 +0200 Message-ID: <20220929144618.1086985-2-marten.lindahl@axis.com> X-Mailer: git-send-email 2.30.2 In-Reply-To: <20220929144618.1086985-1-marten.lindahl@axis.com> References: <20220929144618.1086985-1-marten.lindahl@axis.com> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-pm@vger.kernel.org A device that creates a child character device with cdev_device_add by default create a PM sysfs group with power attributes for userspace control. This means that the power attributes monitors the child device only and thus does not reflect the parent device PM runtime behavior. But as the PM runtime framework (rpm_suspend/rpm_resume) operates not only on a single device that has been enabled for runtime PM, but also on its parent, it should be possible to synchronize the child and the parent so that the power attribute monitoring reflects the child and the parent as one. As an example, if an i2c_client device registers an iio_device, the iio_device will create sysfs power/attribute nodes for userspace control. But if the dev_pm_ops with resume/suspend callbacks is attached to the struct i2c_driver.driver.pm, the PM runtime needs to be enabled for the i2c_client device and not for the child iio_device. In this case PM runtime can be enabled for the i2c_client device and suspend/resume callbacks will be triggered, but the child sysfs power attributes will be visible but marked as 'unsupported' and can not be used for control or monitoring. This can be confusing as the sysfs device node presents the i2c_client and the iio_device as one device. Add a function to synchronize the runtime PM enable state of a device with its parent. As there already exists a link from the child to its parent and both are enabled, all sysfs control/monitoring can reflect both devices, which from a userspace perspective makes more sense. Signed-off-by: Mårten Lindahl --- drivers/base/power/runtime.c | 18 ++++++++++++++++++ include/linux/pm_runtime.h | 2 ++ 2 files changed, 20 insertions(+) diff --git a/drivers/base/power/runtime.c b/drivers/base/power/runtime.c index 997be3ac20a7..b202d513684a 100644 --- a/drivers/base/power/runtime.c +++ b/drivers/base/power/runtime.c @@ -1499,6 +1499,24 @@ void pm_runtime_enable(struct device *dev) } EXPORT_SYMBOL_GPL(pm_runtime_enable); +/** + * pm_runtime_sync_parent_enable - Synchronize enable state. + * @dev: Device to handle. + * + * Synchronize the device enable state with its parent. + * NOTE: This function should only be used if the parent will never disable + * PM runtime (i.e. calling __pm_runtime_disable()) without telling its child. + */ +void pm_runtime_sync_parent_enable(struct device *dev) +{ + struct device *parent = dev->parent; + + if (parent && !parent->power.ignore_children + && pm_runtime_enabled(parent)) + pm_runtime_enable(dev); +} +EXPORT_SYMBOL_GPL(pm_runtime_sync_parent_enable); + static void pm_runtime_disable_action(void *data) { pm_runtime_dont_use_autosuspend(data); diff --git a/include/linux/pm_runtime.h b/include/linux/pm_runtime.h index 0a41b2dcccad..5054427adbd1 100644 --- a/include/linux/pm_runtime.h +++ b/include/linux/pm_runtime.h @@ -89,6 +89,7 @@ extern void pm_runtime_put_suppliers(struct device *dev); extern void pm_runtime_new_link(struct device *dev); extern void pm_runtime_drop_link(struct device_link *link); extern void pm_runtime_release_supplier(struct device_link *link); +extern void pm_runtime_sync_parent_enable(struct device *dev); extern int devm_pm_runtime_enable(struct device *dev); @@ -315,6 +316,7 @@ static inline void pm_runtime_put_suppliers(struct device *dev) {} static inline void pm_runtime_new_link(struct device *dev) {} static inline void pm_runtime_drop_link(struct device_link *link) {} static inline void pm_runtime_release_supplier(struct device_link *link) {} +static inline void pm_runtime_sync_parent_enable(struct device *dev) {} #endif /* !CONFIG_PM */