From 1067183e2071f5d377842a2452680394168bf6fb Mon Sep 17 00:00:00 2001 From: Sudeep Holla Date: Thu, 14 Feb 2019 18:29:10 +0000 Subject: [PATCH] BACKPORT: PM / core: Add support to skip power management in device/driver model All device objects in the driver model contain fields that control the handling of various power management activities. However, it's not always useful. There are few instances where pseudo devices are added to the model just to take advantage of many other features like kobjects, udev events, and so on. One such example is cpu devices and their caches. The sysfs for the cpu caches are managed by adding devices with cpu as the parent in cpu_device_create() when secondary cpu is brought online. Generally when the secondary CPUs are hotplugged back in as part of resume from suspend-to-ram, we call cpu_device_create() from the cpu hotplug state machine while the cpu device associated with that CPU is not yet ready to be resumed as the device_resume() call happens bit later. It's not really needed to set the flag is_prepared for cpu devices as they are mostly pseudo device and hotplug framework deals with state machine and not managed through the cpu device. This often results in annoying warning when resuming: Enabling non-boot CPUs ... CPU1: Booted secondary processor cache: parent cpu1 should not be sleeping CPU1 is up CPU2: Booted secondary processor cache: parent cpu2 should not be sleeping CPU2 is up .... and so on. So in order to fix these kind of errors, we could just completely avoid doing any power management related initialisations and operations if they are not used by these devices. Add no_pm flags to indicate that the device doesn't require any sort of PM activities and all of them can be completely skipped. We can use the same flag to also avoid adding not used *power* sysfs entries for these devices. For now, lets use this for cpu cache devices. Reviewed-by: Ulf Hansson Signed-off-by: Sudeep Holla Tested-by: Eugeniu Rosca Signed-off-by: Rafael J. Wysocki Signed-off-by: Albert I Change-Id: Ia0fcfe47501397c8165a7760de0e4de0b0669699 --- drivers/base/cpu.c | 1 + drivers/base/power/main.c | 7 +++++++ drivers/base/power/sysfs.c | 6 ++++++ include/linux/device.h | 10 ++++++++++ include/linux/pm.h | 1 + 5 files changed, 25 insertions(+) diff --git a/drivers/base/cpu.c b/drivers/base/cpu.c index 88f89a38588a..b7b83c1347a3 100644 --- a/drivers/base/cpu.c +++ b/drivers/base/cpu.c @@ -412,6 +412,7 @@ __cpu_device_create(struct device *parent, void *drvdata, dev->parent = parent; dev->groups = groups; dev->release = device_create_release; + device_set_pm_not_required(dev); dev_set_drvdata(dev, drvdata); retval = kobject_set_name_vargs(&dev->kobj, fmt, args); diff --git a/drivers/base/power/main.c b/drivers/base/power/main.c index 8500a7380e61..810c8f9462b2 100644 --- a/drivers/base/power/main.c +++ b/drivers/base/power/main.c @@ -124,6 +124,10 @@ void device_pm_unlock(void) */ void device_pm_add(struct device *dev) { + /* Skip PM setup/initialization. */ + if (device_pm_not_required(dev)) + return; + pr_debug("PM: Adding info for %s:%s\n", dev->bus ? dev->bus->name : "No Bus", dev_name(dev)); device_pm_check_callbacks(dev); @@ -141,6 +145,9 @@ void device_pm_add(struct device *dev) */ void device_pm_remove(struct device *dev) { + if (device_pm_not_required(dev)) + return; + pr_debug("PM: Removing info for %s:%s\n", dev->bus ? dev->bus->name : "No Bus", dev_name(dev)); complete_all(&dev->power.completion); diff --git a/drivers/base/power/sysfs.c b/drivers/base/power/sysfs.c index 39efa7e6c0c0..9c6e6f0c90ad 100644 --- a/drivers/base/power/sysfs.c +++ b/drivers/base/power/sysfs.c @@ -679,6 +679,10 @@ int dpm_sysfs_add(struct device *dev) { int rc; + /* No need to create PM sysfs if explicitly disabled. */ + if (device_pm_not_required(dev)) + return 0; + rc = sysfs_create_group(&dev->kobj, &pm_attr_group); if (rc) return rc; @@ -758,6 +762,8 @@ void rpm_sysfs_remove(struct device *dev) void dpm_sysfs_remove(struct device *dev) { + if (device_pm_not_required(dev)) + return; sysfs_unmerge_group(&dev->kobj, &pm_qos_latency_tolerance_attr_group); dev_pm_qos_constraints_destroy(dev); rpm_sysfs_remove(dev); diff --git a/include/linux/device.h b/include/linux/device.h index e1f5ecf6fadf..be8e0de7ccc6 100644 --- a/include/linux/device.h +++ b/include/linux/device.h @@ -985,6 +985,16 @@ static inline bool device_async_suspend_enabled(struct device *dev) return !!dev->power.async_suspend; } +static inline bool device_pm_not_required(struct device *dev) +{ + return dev->power.no_pm; +} + +static inline void device_set_pm_not_required(struct device *dev) +{ + dev->power.no_pm = true; +} + static inline void dev_pm_syscore_device(struct device *dev, bool val) { #ifdef CONFIG_PM_SLEEP diff --git a/include/linux/pm.h b/include/linux/pm.h index 5b7964aaf3e8..ca11ec1d922f 100644 --- a/include/linux/pm.h +++ b/include/linux/pm.h @@ -574,6 +574,7 @@ struct dev_pm_info { bool is_suspended:1; /* Ditto */ bool is_noirq_suspended:1; bool is_late_suspended:1; + bool no_pm:1; bool early_init:1; /* Owned by the PM core */ bool direct_complete:1; /* Owned by the PM core */ spinlock_t lock; -- 2.20.1