Date:	Tue, 9 Oct 2012 20:33:23 -0700
From:	mark gross <markgross@...gnar.org>
To:	"Rafael J. Wysocki" <rjw@...k.pl>
Cc:	Linux PM list <linux-pm@...r.kernel.org>,
	ACPI Devel Mailing List <linux-acpi@...r.kernel.org>,
	Alan Stern <stern@...land.harvard.edu>,
	Huang Ying <ying.huang@...el.com>,
	Sarah Sharp <sarah.a.sharp@...ux.intel.com>,
	Lan Tianyu <tianyu.lan@...el.com>,
	Aaron Lu <aaron.lu@...el.com>, Jean Pihet <j-pihet@...com>,
	linux-pci@...r.kernel.org,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	mark gross <markgross@...gnar.org>,
	LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 5/7] PM / QoS: Make it possible to expose PM QoS device
 flags to user space

On Mon, Oct 08, 2012 at 10:07:58AM +0200, Rafael J. Wysocki wrote:
> From: Rafael J. Wysocki <rafael.j.wysocki@...el.com>
> 
> Define two device PM QoS flags, PM_QOS_FLAG_NO_POWER_OFF
> and PM_QOS_FLAG_REMOTE_WAKEUP, and introduce routines
> dev_pm_qos_expose_flags() and dev_pm_qos_hide_flags() allowing the
> caller to expose those two flags to user space or to hide them
> from it, respectively.
> 
> After the flags have been exposed, user space will see two
> additional sysfs attributes, pm_qos_no_power_off and
> pm_qos_remote_wakeup, under the device's /sys/devices/.../power/
> directory.  Then, writing 1 to one of them will update the
> PM QoS flags request owned by user space so that the corresponding
> flag is requested to be set.  In turn, writing 0 to one of them
> will cause the corresponding flag in the user space's request to
> be cleared (however, the owners of the other PM QoS flags requests
> for the same device may still request the flag to be set and it
> may be effectively set even if user space doesn't request that).
> 
> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@...el.com>
> Reviewed-by: Jean Pihet <j-pihet@...com>
> ---
>  Documentation/ABI/testing/sysfs-devices-power |   31 ++++
>  drivers/base/power/power.h                    |    6 
>  drivers/base/power/qos.c                      |  167 ++++++++++++++++++++------
>  drivers/base/power/sysfs.c                    |   95 +++++++++++++-
>  include/linux/pm.h                            |    1 
>  include/linux/pm_qos.h                        |   26 ++++
>  6 files changed, 278 insertions(+), 48 deletions(-)
> 
> Index: linux/include/linux/pm_qos.h
> ===================================================================
> --- linux.orig/include/linux/pm_qos.h
> +++ linux/include/linux/pm_qos.h
> @@ -34,6 +34,9 @@ enum pm_qos_flags_status {
>  #define PM_QOS_NETWORK_THROUGHPUT_DEFAULT_VALUE	0
>  #define PM_QOS_DEV_LAT_DEFAULT_VALUE		0
>  
> +#define PM_QOS_FLAG_NO_POWER_OFF	(1 << 0)
> +#define PM_QOS_FLAG_REMOTE_WAKEUP	(1 << 1)
> +
>  struct pm_qos_request {
>  	struct plist_node node;
>  	int pm_qos_class;
> @@ -86,6 +89,8 @@ struct pm_qos_flags {
>  struct dev_pm_qos {
>  	struct pm_qos_constraints latency;
>  	struct pm_qos_flags flags;
> +	struct dev_pm_qos_request *latency_req;
> +	struct dev_pm_qos_request *flags_req;

I think I'm getting it now.  if someday we have per device throughput
you would have us add a pm_qos_constraints throughput; and a
dev_pm_qos_request *throughput_req;


>  };
>  
>  /* Action requested to pm_qos_update_target */
> @@ -187,10 +192,31 @@ static inline int dev_pm_qos_add_ancesto
>  #ifdef CONFIG_PM_RUNTIME
>  int dev_pm_qos_expose_latency_limit(struct device *dev, s32 value);
>  void dev_pm_qos_hide_latency_limit(struct device *dev);
> +int dev_pm_qos_expose_flags(struct device *dev, s32 value);
> +void dev_pm_qos_hide_flags(struct device *dev);
> +int dev_pm_qos_update_flags(struct device *dev, s32 mask, bool set);
> +
> +static inline s32 dev_pm_qos_requested_latency(struct device *dev)
> +{
> +	return dev->power.qos->latency_req->data.pnode.prio;
> +}
> +
> +static inline s32 dev_pm_qos_requested_flags(struct device *dev)
> +{
> +	return dev->power.qos->flags_req->data.flr.flags;
> +}
>  #else
>  static inline int dev_pm_qos_expose_latency_limit(struct device *dev, s32 value)
>  			{ return 0; }
>  static inline void dev_pm_qos_hide_latency_limit(struct device *dev) {}
> +static inline int dev_pm_qos_expose_flags(struct device *dev, s32 value)
> +			{ return 0; }
> +static inline void dev_pm_qos_hide_flags(struct device *dev) {}
> +static inline int dev_pm_qos_update_flags(struct device *dev, s32 m, bool set)
> +			{ return 0; }
> +
> +static inline s32 dev_pm_qos_requested_latency(struct device *dev) { return 0; }
> +static inline s32 dev_pm_qos_requested_flags(struct device *dev) { return 0; }
>  #endif
>  
>  #endif
> Index: linux/include/linux/pm.h
> ===================================================================
> --- linux.orig/include/linux/pm.h
> +++ linux/include/linux/pm.h
> @@ -548,7 +548,6 @@ struct dev_pm_info {
>  	unsigned long		active_jiffies;
>  	unsigned long		suspended_jiffies;
>  	unsigned long		accounting_timestamp;
> -	struct dev_pm_qos_request *pq_req;
>  #endif
>  	struct pm_subsys_data	*subsys_data;  /* Owned by the subsystem. */
>  	struct dev_pm_qos	*qos;
> Index: linux/drivers/base/power/qos.c
> ===================================================================
> --- linux.orig/drivers/base/power/qos.c
> +++ linux/drivers/base/power/qos.c
> @@ -40,6 +40,7 @@
>  #include <linux/device.h>
>  #include <linux/mutex.h>
>  #include <linux/export.h>
> +#include <linux/pm_runtime.h>
>  
>  #include "power.h"
>  
> @@ -322,6 +323,36 @@ int dev_pm_qos_add_request(struct device
>  EXPORT_SYMBOL_GPL(dev_pm_qos_add_request);
>  
>  /**
> + * __dev_pm_qos_update_request - Modify an existing device PM QoS request.
> + * @req : PM QoS request to modify.
> + * @new_value: New value to request.
> + */
> +int __dev_pm_qos_update_request(struct dev_pm_qos_request *req, s32 new_value)
> +{
> +	s32 curr_value;
> +	int ret = 0;
> +
> +	if (!req->dev->power.qos)
> +		return -ENODEV;
> +
> +	switch(req->type) {
> +	case DEV_PM_QOS_LATENCY:
> +		curr_value = req->data.pnode.prio;
> +		break;
> +	case DEV_PM_QOS_FLAGS:
> +		curr_value = req->data.flr.flags;
> +		break;
> +	default:
> +		return -EINVAL;
> +	}
> +
> +	if (curr_value != new_value)
> +		ret = apply_constraint(req, PM_QOS_UPDATE_REQ, new_value);
> +
> +	return ret;
> +}
> +
> +/**
>   * dev_pm_qos_update_request - modifies an existing qos request
>   * @req : handle to list element holding a dev_pm_qos request to use
>   * @new_value: defines the qos request
> @@ -336,11 +367,9 @@ EXPORT_SYMBOL_GPL(dev_pm_qos_add_request
>   * -EINVAL in case of wrong parameters, -ENODEV if the device has been
>   * removed from the system
>   */
> -int dev_pm_qos_update_request(struct dev_pm_qos_request *req,
> -			      s32 new_value)
> +int dev_pm_qos_update_request(struct dev_pm_qos_request *req, s32 new_value)
>  {
> -	s32 curr_value;
> -	int ret = 0;
> +	int ret;
>  
>  	if (!req) /*guard against callers passing in null */
>  		return -EINVAL;
> @@ -350,29 +379,9 @@ int dev_pm_qos_update_request(struct dev
>  		return -EINVAL;
>  
>  	mutex_lock(&dev_pm_qos_mtx);
> -
> -	if (!req->dev->power.qos) {
> -		ret = -ENODEV;
> -		goto out;
> -	}
> -
> -	switch(req->type) {
> -	case DEV_PM_QOS_LATENCY:
> -		curr_value = req->data.pnode.prio;
> -		break;
> -	case DEV_PM_QOS_FLAGS:
> -		curr_value = req->data.flr.flags;
> -		break;
> -	default:
> -		ret = -EINVAL;
> -		goto out;
> -	}
> -
> -	if (curr_value != new_value)
> -		ret = apply_constraint(req, PM_QOS_UPDATE_REQ, new_value);
> -
> - out:
> +	__dev_pm_qos_update_request(req, new_value);
>  	mutex_unlock(&dev_pm_qos_mtx);
> +
>  	return ret;
>  }
>  EXPORT_SYMBOL_GPL(dev_pm_qos_update_request);
> @@ -533,10 +542,19 @@ int dev_pm_qos_add_ancestor_request(stru
>  EXPORT_SYMBOL_GPL(dev_pm_qos_add_ancestor_request);
>  
>  #ifdef CONFIG_PM_RUNTIME
> -static void __dev_pm_qos_drop_user_request(struct device *dev)
> +static void __dev_pm_qos_drop_user_request(struct device *dev,
> +					   enum dev_pm_qos_req_type type)
>  {
> -	dev_pm_qos_remove_request(dev->power.pq_req);
> -	dev->power.pq_req = NULL;
> +	switch(type) {
> +	case DEV_PM_QOS_LATENCY:
> +		dev_pm_qos_remove_request(dev->power.qos->latency_req);
> +		dev->power.qos->latency_req = NULL;
> +		break;
> +	case DEV_PM_QOS_FLAGS:
> +		dev_pm_qos_remove_request(dev->power.qos->flags_req);
> +		dev->power.qos->flags_req = NULL;
> +		break;
> +	}
>  }
>  
>  /**
> @@ -552,7 +570,7 @@ int dev_pm_qos_expose_latency_limit(stru
>  	if (!device_is_registered(dev) || value < 0)
>  		return -EINVAL;
>  
> -	if (dev->power.pq_req)
> +	if (dev->power.qos && dev->power.qos->latency_req)
>  		return -EEXIST;
>  
>  	req = kzalloc(sizeof(*req), GFP_KERNEL);
> @@ -563,10 +581,10 @@ int dev_pm_qos_expose_latency_limit(stru
>  	if (ret < 0)
>  		return ret;
>  
> -	dev->power.pq_req = req;
> -	ret = pm_qos_sysfs_add(dev);
> +	dev->power.qos->latency_req = req;
> +	ret = pm_qos_sysfs_add_latency(dev);
>  	if (ret)
> -		__dev_pm_qos_drop_user_request(dev);
> +		__dev_pm_qos_drop_user_request(dev, DEV_PM_QOS_LATENCY);
>  
>  	return ret;
>  }
> @@ -578,10 +596,87 @@ EXPORT_SYMBOL_GPL(dev_pm_qos_expose_late
>   */
>  void dev_pm_qos_hide_latency_limit(struct device *dev)
>  {
> -	if (dev->power.pq_req) {
> -		pm_qos_sysfs_remove(dev);
> -		__dev_pm_qos_drop_user_request(dev);
> +	if (dev->power.qos && dev->power.qos->latency_req) {
> +		pm_qos_sysfs_remove_latency(dev);
> +		__dev_pm_qos_drop_user_request(dev, DEV_PM_QOS_LATENCY);
>  	}
>  }
>  EXPORT_SYMBOL_GPL(dev_pm_qos_hide_latency_limit);
> +
> +/**
> + * dev_pm_qos_expose_flags - Expose PM QoS flags of a device to user space.
> + * @dev: Device whose PM QoS flags are to be exposed to user space.
> + * @val: Initial values of the flags.
> + */
> +int dev_pm_qos_expose_flags(struct device *dev, s32 val)
> +{
> +	struct dev_pm_qos_request *req;
> +	int ret;
> +
> +	if (!device_is_registered(dev))
> +		return -EINVAL;
> +
> +	if (dev->power.qos && dev->power.qos->flags_req)
> +		return -EEXIST;
> +
> +	req = kzalloc(sizeof(*req), GFP_KERNEL);
> +	if (!req)
> +		return -ENOMEM;
> +
> +	ret = dev_pm_qos_add_request(dev, req, DEV_PM_QOS_FLAGS, val);
> +	if (ret < 0)
> +		return ret;
> +
> +	dev->power.qos->flags_req = req;
> +	ret = pm_qos_sysfs_add_flags(dev);
> +	if (ret)
> +		__dev_pm_qos_drop_user_request(dev, DEV_PM_QOS_FLAGS);
> +
> +	return ret;
> +}
> +EXPORT_SYMBOL_GPL(dev_pm_qos_expose_flags);
> +
> +/**
> + * dev_pm_qos_hide_flags - Hide PM QoS flags of a device from user space.
> + * @dev: Device whose PM QoS flags are to be hidden from user space.
> + */
> +void dev_pm_qos_hide_flags(struct device *dev)
> +{
> +	if (dev->power.qos && dev->power.qos->flags_req) {
> +		pm_qos_sysfs_remove_flags(dev);
> +		__dev_pm_qos_drop_user_request(dev, DEV_PM_QOS_FLAGS);
> +	}
> +}
> +EXPORT_SYMBOL_GPL(dev_pm_qos_hide_flags);
> +
> +/**
> + * dev_pm_qos_update_flags - Update PM QoS flags request owned by user space.
> + * @dev: Device to update the PM QoS flags request for.
> + * @mask: Flags to set/clear.
> + * @set: Whether to set or clear the flags (true means set).
> + */
> +int dev_pm_qos_update_flags(struct device *dev, s32 mask, bool set)
> +{
> +	s32 value;
> +	int ret;
> +
> +	if (!dev->power.qos || !dev->power.qos->flags_req)
> +		return -EINVAL;
> +
> +	pm_runtime_get_sync(dev);
> +	mutex_lock(&dev_pm_qos_mtx);
> +
> +	value = dev_pm_qos_requested_flags(dev);
> +	if (set)
> +		value |= mask;
> +	else
> +		value &= ~mask;
> +
> +	ret = __dev_pm_qos_update_request(dev->power.qos->flags_req, value);
> +
> +	mutex_unlock(&dev_pm_qos_mtx);
> +	pm_runtime_put(dev);
> +
> +	return ret;
> +}
>  #endif /* CONFIG_PM_RUNTIME */
> Index: linux/drivers/base/power/power.h
> ===================================================================
> --- linux.orig/drivers/base/power/power.h
> +++ linux/drivers/base/power/power.h
> @@ -93,8 +93,10 @@ extern void dpm_sysfs_remove(struct devi
>  extern void rpm_sysfs_remove(struct device *dev);
>  extern int wakeup_sysfs_add(struct device *dev);
>  extern void wakeup_sysfs_remove(struct device *dev);
> -extern int pm_qos_sysfs_add(struct device *dev);
> -extern void pm_qos_sysfs_remove(struct device *dev);
> +extern int pm_qos_sysfs_add_latency(struct device *dev);
> +extern void pm_qos_sysfs_remove_latency(struct device *dev);
> +extern int pm_qos_sysfs_add_flags(struct device *dev);
> +extern void pm_qos_sysfs_remove_flags(struct device *dev);
>  
>  #else /* CONFIG_PM */
>  
> Index: linux/drivers/base/power/sysfs.c
> ===================================================================
> --- linux.orig/drivers/base/power/sysfs.c
> +++ linux/drivers/base/power/sysfs.c
> @@ -221,7 +221,7 @@ static DEVICE_ATTR(autosuspend_delay_ms,
>  static ssize_t pm_qos_latency_show(struct device *dev,
>  				   struct device_attribute *attr, char *buf)
>  {
> -	return sprintf(buf, "%d\n", dev->power.pq_req->data.pnode.prio);
> +	return sprintf(buf, "%d\n", dev_pm_qos_requested_latency(dev));
>  }
>  
>  static ssize_t pm_qos_latency_store(struct device *dev,
> @@ -237,12 +237,67 @@ static ssize_t pm_qos_latency_store(stru
>  	if (value < 0)
>  		return -EINVAL;
>  
> -	ret = dev_pm_qos_update_request(dev->power.pq_req, value);
> +	ret = dev_pm_qos_update_request(dev->power.qos->latency_req, value);
>  	return ret < 0 ? ret : n;
>  }
>  
>  static DEVICE_ATTR(pm_qos_resume_latency_us, 0644,
>  		   pm_qos_latency_show, pm_qos_latency_store);
> +
> +static ssize_t pm_qos_no_power_off_show(struct device *dev,
> +					struct device_attribute *attr,
> +					char *buf)
> +{
> +	return sprintf(buf, "%d\n", !!(dev_pm_qos_requested_flags(dev)
> +					& PM_QOS_FLAG_NO_POWER_OFF));
> +}
> +
> +static ssize_t pm_qos_no_power_off_store(struct device *dev,
> +					 struct device_attribute *attr,
> +					 const char *buf, size_t n)
> +{
> +	int ret;
> +
> +	if (kstrtoint(buf, 0, &ret))
> +		return -EINVAL;
> +
> +	if (ret != 0 && ret != 1)
> +		return -EINVAL;
> +
> +	ret = dev_pm_qos_update_flags(dev, PM_QOS_FLAG_NO_POWER_OFF, ret);
> +	return ret < 0 ? ret : n;
> +}
> +
> +static DEVICE_ATTR(pm_qos_no_power_off, 0644,
> +		   pm_qos_no_power_off_show, pm_qos_no_power_off_store);
> +
> +static ssize_t pm_qos_remote_wakeup_show(struct device *dev,
> +					 struct device_attribute *attr,
> +					 char *buf)
> +{
> +	return sprintf(buf, "%d\n", !!(dev_pm_qos_requested_flags(dev)
> +					& PM_QOS_FLAG_REMOTE_WAKEUP));
> +}
> +
> +static ssize_t pm_qos_remote_wakeup_store(struct device *dev,
> +					  struct device_attribute *attr,
> +					  const char *buf, size_t n)
> +{
> +	s32 value;
> +	int ret;
> +
> +	if (kstrtoint(buf, 0, &ret))
> +		return -EINVAL;
> +
> +	if (ret != 0 && ret != 1)
> +		return -EINVAL;
> +
> +	ret = dev_pm_qos_update_flags(dev, PM_QOS_FLAG_REMOTE_WAKEUP, ret);
> +	return ret < 0 ? ret : n;
> +}
> +
> +static DEVICE_ATTR(pm_qos_remote_wakeup, 0644,
> +		   pm_qos_remote_wakeup_show, pm_qos_remote_wakeup_store);
>  #endif /* CONFIG_PM_RUNTIME */
>  
>  #ifdef CONFIG_PM_SLEEP
> @@ -564,15 +619,27 @@ static struct attribute_group pm_runtime
>  	.attrs	= runtime_attrs,
>  };
>  
> -static struct attribute *pm_qos_attrs[] = {
> +static struct attribute *pm_qos_latency_attrs[] = {
>  #ifdef CONFIG_PM_RUNTIME
>  	&dev_attr_pm_qos_resume_latency_us.attr,
>  #endif /* CONFIG_PM_RUNTIME */
>  	NULL,
>  };
> -static struct attribute_group pm_qos_attr_group = {
> +static struct attribute_group pm_qos_latency_attr_group = {
> +	.name	= power_group_name,
> +	.attrs	= pm_qos_latency_attrs,
> +};
> +
> +static struct attribute *pm_qos_flags_attrs[] = {
> +#ifdef CONFIG_PM_RUNTIME
> +	&dev_attr_pm_qos_no_power_off.attr,
> +	&dev_attr_pm_qos_remote_wakeup.attr,
> +#endif /* CONFIG_PM_RUNTIME */
> +	NULL,
> +};
> +static struct attribute_group pm_qos_flags_attr_group = {
>  	.name	= power_group_name,
> -	.attrs	= pm_qos_attrs,
> +	.attrs	= pm_qos_flags_attrs,
>  };
>  
>  int dpm_sysfs_add(struct device *dev)
> @@ -615,14 +682,24 @@ void wakeup_sysfs_remove(struct device *
>  	sysfs_unmerge_group(&dev->kobj, &pm_wakeup_attr_group);
>  }
>  
> -int pm_qos_sysfs_add(struct device *dev)
> +int pm_qos_sysfs_add_latency(struct device *dev)
> +{
> +	return sysfs_merge_group(&dev->kobj, &pm_qos_latency_attr_group);
> +}
> +
> +void pm_qos_sysfs_remove_latency(struct device *dev)
> +{
> +	sysfs_unmerge_group(&dev->kobj, &pm_qos_latency_attr_group);
> +}
> +
> +int pm_qos_sysfs_add_flags(struct device *dev)
>  {
> -	return sysfs_merge_group(&dev->kobj, &pm_qos_attr_group);
> +	return sysfs_merge_group(&dev->kobj, &pm_qos_flags_attr_group);
>  }
>  
> -void pm_qos_sysfs_remove(struct device *dev)
> +void pm_qos_sysfs_remove_flags(struct device *dev)
>  {
> -	sysfs_unmerge_group(&dev->kobj, &pm_qos_attr_group);
> +	sysfs_unmerge_group(&dev->kobj, &pm_qos_flags_attr_group);
>  }
>  
>  void rpm_sysfs_remove(struct device *dev)
> Index: linux/Documentation/ABI/testing/sysfs-devices-power
> ===================================================================
> --- linux.orig/Documentation/ABI/testing/sysfs-devices-power
> +++ linux/Documentation/ABI/testing/sysfs-devices-power
> @@ -204,3 +204,34 @@ Description:
>  
>  		This attribute has no effect on system-wide suspend/resume and
>  		hibernation.
> +
> +What:		/sys/devices/.../power/pm_qos_no_power_off
> +Date:		September 2012
> +Contact:	Rafael J. Wysocki <rjw@...k.pl>
> +Description:
> +		The /sys/devices/.../power/pm_qos_no_power_off attribute
> +		is used for manipulating the PM QoS "no power off" flag.  If
> +		set, this flag indicates to the kernel that power should not
> +		be removed entirely from the device.
> +
> +		Not all drivers support this attribute.  If it isn't supported,
> +		it is not present.
> +
> +		This attribute has no effect on system-wide suspend/resume and
> +		hibernation.
> +
> +What:		/sys/devices/.../power/pm_qos_remote_wakeup
> +Date:		September 2012
> +Contact:	Rafael J. Wysocki <rjw@...k.pl>
> +Description:
> +		The /sys/devices/.../power/pm_qos_remote_wakeup attribute
> +		is used for manipulating the PM QoS "remote wakeup required"
> +		flag.  If set, this flag indicates to the kernel that the
> +		device is a source of user events that have to be signaled from
> +		its low-power states.
> +
> +		Not all drivers support this attribute.  If it isn't supported,
> +		it is not present.
> +
> +		This attribute has no effect on system-wide suspend/resume and
> +		hibernation.
>
acked-by: mark gross <markgross@...gnar.org>

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