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Date: Tue, 18 Jan 2011 02:50:05 +0200
From: Maxim Levitsky <maximlevitsky@...il.com>
To: "Rafael J. Wysocki" <rjw@...k.pl>
Cc: Alan Stern <stern@...land.harvard.edu>,
Linux-pm mailing list <linux-pm@...ts.linux-foundation.org>,
Len Brown <lenb@...nel.org>,
LKML <linux-kernel@...r.kernel.org>
Subject: Re: [RFC][PATCH] PM: Do not create wakeup sysfs files for devices
that cannot wakeup
On Sat, 2011-01-15 at 01:08 +0100, Rafael J. Wysocki wrote:
> On Friday, January 14, 2011, Alan Stern wrote:
> > On Fri, 14 Jan 2011, Rafael J. Wysocki wrote:
I welcome that change very well.
It was always driving me nuts seeing these empty wakeup files.
Best regards,
Maxim Levitsky
> ...
> > ...
> >
> > > static struct attribute *runtime_attrs[] = {
> > > -#ifndef CONFIG_PM_ADVANCED_DEBUG
> > > +#ifdef CONFIG_PM_RUNTIME
> > > &dev_attr_runtime_status.attr,
> > > -#endif
> > > &dev_attr_control.attr,
> > > &dev_attr_runtime_suspended_time.attr,
> > > &dev_attr_runtime_active_time.attr,
> > > &dev_attr_autosuspend_delay_ms.attr,
> > > +#ifdef CONFIG_PM_ADVANCED_DEBUG
> > > + &dev_attr_runtime_usage.attr,
> > > + &dev_attr_runtime_active_kids.attr,
> > > + &dev_attr_runtime_enabled.attr,
> > > +#endif
> > > +#endif /* CONFIG_PM_RUNTIME */
> > > NULL,
> > > };
> > > static struct attribute_group pm_runtime_attr_group = {
> > > @@ -480,35 +485,49 @@ int dpm_sysfs_add(struct device *dev)
> > > int rc;
> > >
> > > rc = sysfs_create_group(&dev->kobj, &pm_attr_group);
> > > - if (rc == 0 && !dev->power.no_callbacks) {
> > > + if (rc)
> > > + return rc;
> > > +
> > > + if (pm_runtime_callbacks_present(dev)) {
> > > rc = sysfs_merge_group(&dev->kobj, &pm_runtime_attr_group);
> > > if (rc)
> > > - sysfs_remove_group(&dev->kobj, &pm_attr_group);
> > > + goto err_out;
> > > + }
> >
> > One thing I don't like about this change. The original code defines
> > runtime_status, runtime_usage, runtime_active_kids, and runtime_enabled
> > whenever PM_RUNTIME and PM_ADVANCED_DEBUG are set. Now you don't
> > define these attributes if runtime callbacks aren't present, even
> > though they would still make sense. Maybe you should have two
> > runtime-related attribute groups, where one depends on
> > callbacks_present and the other doesn't.
>
> OK, I think that problem is not present any more in the new version of the
> patch, which is appended.
>
> > Apart from that, it all seems reasonable. But you should change the
> > description of the wakeup attribute in Documentation/power/devices.txt;
> > it says that the attribute file is present but empty if the device is
> > not wakeup-capable.
>
> Right and not only that. The descriptions in ABI/sysfs-device-power have to be
> updated too.
>
> Thanks,
> Rafael
>
> ---
> From: Rafael J. Wysocki <rjw@...k.pl>
> Subject: PM: Do not create wakeup sysfs files for devices that cannot wake up
>
> Currently, wakeup sysfs attributes are created for all devices,
> regardless of whether or not they are wakeup-capable. This is
> excessive and complicates wakeup device identification from user
> space (i.e. to identify wakeup-capable devices user space has to read
> /sys/devices/.../power/wakeup for all devices and see if they are not
> empty).
>
> Fix this issue by avoiding to create wakeup sysfs files for devices
> that cannot wake up the system from sleep states (i.e. whose
> power.can_wakeup flags are unset during registration) and modify
> device_set_wakeup_capable() so that it adds (or removes) the relevant
> sysfs attributes if a device's wakeup capability status is changed.
>
> Signed-off-by: Rafael J. Wysocki <rjw@...k.pl>
> ---
> Documentation/ABI/testing/sysfs-devices-power | 20 +++---
> Documentation/power/devices.txt | 20 +++---
> drivers/base/power/power.h | 15 ++---
> drivers/base/power/sysfs.c | 78 +++++++++++++++++---------
> drivers/base/power/wakeup.c | 26 ++++++++
> include/linux/pm_runtime.h | 6 ++
> include/linux/pm_wakeup.h | 10 ---
> 7 files changed, 112 insertions(+), 63 deletions(-)
>
> Index: linux-2.6/drivers/base/power/sysfs.c
> ===================================================================
> --- linux-2.6.orig/drivers/base/power/sysfs.c
> +++ linux-2.6/drivers/base/power/sysfs.c
> @@ -431,26 +431,18 @@ static ssize_t async_store(struct device
> static DEVICE_ATTR(async, 0644, async_show, async_store);
> #endif /* CONFIG_PM_ADVANCED_DEBUG */
>
> -static struct attribute * power_attrs[] = {
> - &dev_attr_wakeup.attr,
> -#ifdef CONFIG_PM_SLEEP
> - &dev_attr_wakeup_count.attr,
> - &dev_attr_wakeup_active_count.attr,
> - &dev_attr_wakeup_hit_count.attr,
> - &dev_attr_wakeup_active.attr,
> - &dev_attr_wakeup_total_time_ms.attr,
> - &dev_attr_wakeup_max_time_ms.attr,
> - &dev_attr_wakeup_last_time_ms.attr,
> -#endif
> +static struct attribute *power_attrs[] = {
> #ifdef CONFIG_PM_ADVANCED_DEBUG
> +#ifdef CONFIG_PM_SLEEP
> &dev_attr_async.attr,
> +#endif
> #ifdef CONFIG_PM_RUNTIME
> &dev_attr_runtime_status.attr,
> &dev_attr_runtime_usage.attr,
> &dev_attr_runtime_active_kids.attr,
> &dev_attr_runtime_enabled.attr,
> #endif
> -#endif
> +#endif /* CONFIG_PM_ADVANCED_DEBUG */
> NULL,
> };
> static struct attribute_group pm_attr_group = {
> @@ -458,9 +450,26 @@ static struct attribute_group pm_attr_gr
> .attrs = power_attrs,
> };
>
> -#ifdef CONFIG_PM_RUNTIME
> +static struct attribute *wakeup_attrs[] = {
> +#ifdef CONFIG_PM_SLEEP
> + &dev_attr_wakeup.attr,
> + &dev_attr_wakeup_count.attr,
> + &dev_attr_wakeup_active_count.attr,
> + &dev_attr_wakeup_hit_count.attr,
> + &dev_attr_wakeup_active.attr,
> + &dev_attr_wakeup_total_time_ms.attr,
> + &dev_attr_wakeup_max_time_ms.attr,
> + &dev_attr_wakeup_last_time_ms.attr,
> +#endif
> + NULL,
> +};
> +static struct attribute_group pm_wakeup_attr_group = {
> + .name = power_group_name,
> + .attrs = wakeup_attrs,
> +};
>
> static struct attribute *runtime_attrs[] = {
> +#ifdef CONFIG_PM_RUNTIME
> #ifndef CONFIG_PM_ADVANCED_DEBUG
> &dev_attr_runtime_status.attr,
> #endif
> @@ -468,6 +477,7 @@ static struct attribute *runtime_attrs[]
> &dev_attr_runtime_suspended_time.attr,
> &dev_attr_runtime_active_time.attr,
> &dev_attr_autosuspend_delay_ms.attr,
> +#endif /* CONFIG_PM_RUNTIME */
> NULL,
> };
> static struct attribute_group pm_runtime_attr_group = {
> @@ -480,35 +490,49 @@ int dpm_sysfs_add(struct device *dev)
> int rc;
>
> rc = sysfs_create_group(&dev->kobj, &pm_attr_group);
> - if (rc == 0 && !dev->power.no_callbacks) {
> + if (rc)
> + return rc;
> +
> + if (pm_runtime_callbacks_present(dev)) {
> rc = sysfs_merge_group(&dev->kobj, &pm_runtime_attr_group);
> if (rc)
> - sysfs_remove_group(&dev->kobj, &pm_attr_group);
> + goto err_out;
> + }
> +
> + if (device_can_wakeup(dev)) {
> + rc = sysfs_merge_group(&dev->kobj, &pm_wakeup_attr_group);
> + if (rc) {
> + if (pm_runtime_callbacks_present(dev))
> + sysfs_unmerge_group(&dev->kobj,
> + &pm_runtime_attr_group);
> + goto err_out;
> + }
> }
> + return 0;
> +
> + err_out:
> + sysfs_remove_group(&dev->kobj, &pm_attr_group);
> return rc;
> }
>
> -void rpm_sysfs_remove(struct device *dev)
> +int wakeup_sysfs_add(struct device *dev)
> {
> - sysfs_unmerge_group(&dev->kobj, &pm_runtime_attr_group);
> + return sysfs_merge_group(&dev->kobj, &pm_wakeup_attr_group);
> }
>
> -void dpm_sysfs_remove(struct device *dev)
> +void wakeup_sysfs_remove(struct device *dev)
> {
> - rpm_sysfs_remove(dev);
> - sysfs_remove_group(&dev->kobj, &pm_attr_group);
> + sysfs_unmerge_group(&dev->kobj, &pm_wakeup_attr_group);
> }
>
> -#else /* CONFIG_PM_RUNTIME */
> -
> -int dpm_sysfs_add(struct device * dev)
> +void rpm_sysfs_remove(struct device *dev)
> {
> - return sysfs_create_group(&dev->kobj, &pm_attr_group);
> + sysfs_unmerge_group(&dev->kobj, &pm_runtime_attr_group);
> }
>
> -void dpm_sysfs_remove(struct device * dev)
> +void dpm_sysfs_remove(struct device *dev)
> {
> + rpm_sysfs_remove(dev);
> + sysfs_unmerge_group(&dev->kobj, &pm_wakeup_attr_group);
> sysfs_remove_group(&dev->kobj, &pm_attr_group);
> }
> -
> -#endif
> Index: linux-2.6/include/linux/pm_runtime.h
> ===================================================================
> --- linux-2.6.orig/include/linux/pm_runtime.h
> +++ linux-2.6/include/linux/pm_runtime.h
> @@ -87,6 +87,11 @@ static inline bool pm_runtime_enabled(st
> return !dev->power.disable_depth;
> }
>
> +static inline bool pm_runtime_callbacks_present(struct device *dev)
> +{
> + return !dev->power.no_callbacks;
> +}
> +
> static inline void pm_runtime_mark_last_busy(struct device *dev)
> {
> ACCESS_ONCE(dev->power.last_busy) = jiffies;
> @@ -133,6 +138,7 @@ static inline int pm_generic_runtime_res
> static inline void pm_runtime_no_callbacks(struct device *dev) {}
> static inline void pm_runtime_irq_safe(struct device *dev) {}
>
> +static inline bool pm_runtime_callbacks_present(struct device *dev) { return false; }
> static inline void pm_runtime_mark_last_busy(struct device *dev) {}
> static inline void __pm_runtime_use_autosuspend(struct device *dev,
> bool use) {}
> Index: linux-2.6/drivers/base/power/power.h
> ===================================================================
> --- linux-2.6.orig/drivers/base/power/power.h
> +++ linux-2.6/drivers/base/power/power.h
> @@ -61,16 +61,15 @@ static inline void device_pm_move_last(s
> extern int dpm_sysfs_add(struct device *);
> extern void dpm_sysfs_remove(struct device *);
> extern void rpm_sysfs_remove(struct device *);
> +extern int wakeup_sysfs_add(struct device *dev);
> +extern void wakeup_sysfs_remove(struct device *dev);
>
> #else /* CONFIG_PM */
>
> -static inline int dpm_sysfs_add(struct device *dev)
> -{
> - return 0;
> -}
> -
> -static inline void dpm_sysfs_remove(struct device *dev)
> -{
> -}
> +static inline int dpm_sysfs_add(struct device *dev) { return 0; }
> +static inline void dpm_sysfs_remove(struct device *dev) {}
> +static inline void rpm_sysfs_remove(struct device *) {}
> +static inline int wakeup_sysfs_add(struct device *dev) { return 0; }
> +static inline void wakeup_sysfs_remove(struct device *dev) {}
>
> #endif
> Index: linux-2.6/include/linux/pm_wakeup.h
> ===================================================================
> --- linux-2.6.orig/include/linux/pm_wakeup.h
> +++ linux-2.6/include/linux/pm_wakeup.h
> @@ -62,18 +62,11 @@ struct wakeup_source {
> * Changes to device_may_wakeup take effect on the next pm state change.
> */
>
> -static inline void device_set_wakeup_capable(struct device *dev, bool capable)
> -{
> - dev->power.can_wakeup = capable;
> -}
> -
> static inline bool device_can_wakeup(struct device *dev)
> {
> return dev->power.can_wakeup;
> }
>
> -
> -
> static inline bool device_may_wakeup(struct device *dev)
> {
> return dev->power.can_wakeup && !!dev->power.wakeup;
> @@ -88,6 +81,7 @@ extern struct wakeup_source *wakeup_sour
> extern void wakeup_source_unregister(struct wakeup_source *ws);
> extern int device_wakeup_enable(struct device *dev);
> extern int device_wakeup_disable(struct device *dev);
> +extern void device_set_wakeup_capable(struct device *dev, bool capable);
> extern int device_init_wakeup(struct device *dev, bool val);
> extern int device_set_wakeup_enable(struct device *dev, bool enable);
> extern void __pm_stay_awake(struct wakeup_source *ws);
> @@ -144,7 +138,7 @@ static inline int device_wakeup_disable(
>
> static inline int device_init_wakeup(struct device *dev, bool val)
> {
> - dev->power.can_wakeup = val;
> + device_set_wakeup_capable(dev, val);
> return val ? -EINVAL : 0;
> }
>
> Index: linux-2.6/drivers/base/power/wakeup.c
> ===================================================================
> --- linux-2.6.orig/drivers/base/power/wakeup.c
> +++ linux-2.6/drivers/base/power/wakeup.c
> @@ -228,6 +228,32 @@ int device_wakeup_disable(struct device
> EXPORT_SYMBOL_GPL(device_wakeup_disable);
>
> /**
> + * device_set_wakeup_capable - Set/reset device wakeup capability flag.
> + * @dev: Device to handle.
> + * @capable: Whether or not @dev is capable of waking up the system from sleep.
> + *
> + * If @capable is set, set the @dev's power.can_wakeup flag and add its
> + * wakeup-related attributes to sysfs. Otherwise, unset the @dev's
> + * power.can_wakeup flag and remove its wakeup-related attributes from sysfs.
> + */
> +void device_set_wakeup_capable(struct device *dev, bool capable)
> +{
> + if (!!dev->power.can_wakeup == !!capable)
> + return;
> +
> + if (device_is_registered(dev)) {
> + if (capable) {
> + if (wakeup_sysfs_add(dev))
> + return;
> + } else {
> + wakeup_sysfs_remove(dev);
> + }
> + }
> + dev->power.can_wakeup = capable;
> +}
> +EXPORT_SYMBOL_GPL(device_set_wakeup_capable);
> +
> +/**
> * device_init_wakeup - Device wakeup initialization.
> * @dev: Device to handle.
> * @enable: Whether or not to enable @dev as a wakeup device.
> Index: linux-2.6/Documentation/power/devices.txt
> ===================================================================
> --- linux-2.6.orig/Documentation/power/devices.txt
> +++ linux-2.6/Documentation/power/devices.txt
> @@ -159,18 +159,18 @@ matter, and the kernel is responsible fo
> whether or not a wakeup-capable device should issue wakeup events is a policy
> decision, and it is managed by user space through a sysfs attribute: the
> power/wakeup file. User space can write the strings "enabled" or "disabled" to
> -set or clear the should_wakeup flag, respectively. Reads from the file will
> -return the corresponding string if can_wakeup is true, but if can_wakeup is
> -false then reads will return an empty string, to indicate that the device
> -doesn't support wakeup events. (But even though the file appears empty, writes
> -will still affect the should_wakeup flag.)
> +set or clear the "should_wakeup" flag, respectively. This file is only present
> +for wakeup-capable devices (i.e. devices whose "can_wakeup" flags are set)
> +and is created (or removed) by device_set_wakeup_capable(). Reads from the
> +file will return the corresponding string.
>
> The device_may_wakeup() routine returns true only if both flags are set.
> -Drivers should check this routine when putting devices in a low-power state
> -during a system sleep transition, to see whether or not to enable the devices'
> -wakeup mechanisms. However for runtime power management, wakeup events should
> -be enabled whenever the device and driver both support them, regardless of the
> -should_wakeup flag.
> +This information is used by subsystems, like the PCI bus type code, to see
> +whether or not to enable the devices' wakeup mechanisms. If device wakeup
> +mechanisms are enabled or disabled directly by drivers, they also should use
> +device_may_wakeup() to decide what to do during a system sleep transition.
> +However for runtime power management, wakeup events should be enabled whenever
> +the device and driver both support them, regardless of the should_wakeup flag.
>
>
> /sys/devices/.../power/control files
> Index: linux-2.6/Documentation/ABI/testing/sysfs-devices-power
> ===================================================================
> --- linux-2.6.orig/Documentation/ABI/testing/sysfs-devices-power
> +++ linux-2.6/Documentation/ABI/testing/sysfs-devices-power
> @@ -29,9 +29,8 @@ Description:
> "disabled" to it.
>
> For the devices that are not capable of generating system wakeup
> - events this file contains "\n". In that cases the user space
> - cannot modify the contents of this file and the device cannot be
> - enabled to wake up the system.
> + events this file is not present. In that case the device cannot
> + be enabled to wake up the system from sleep states.
>
> What: /sys/devices/.../power/control
> Date: January 2009
> @@ -85,7 +84,7 @@ Description:
> The /sys/devices/.../wakeup_count attribute contains the number
> of signaled wakeup events associated with the device. This
> attribute is read-only. If the device is not enabled to wake up
> - the system from sleep states, this attribute is empty.
> + the system from sleep states, this attribute is not present.
>
> What: /sys/devices/.../power/wakeup_active_count
> Date: September 2010
> @@ -95,7 +94,7 @@ Description:
> number of times the processing of wakeup events associated with
> the device was completed (at the kernel level). This attribute
> is read-only. If the device is not enabled to wake up the
> - system from sleep states, this attribute is empty.
> + system from sleep states, this attribute is not present.
>
> What: /sys/devices/.../power/wakeup_hit_count
> Date: September 2010
> @@ -105,7 +104,8 @@ Description:
> number of times the processing of a wakeup event associated with
> the device might prevent the system from entering a sleep state.
> This attribute is read-only. If the device is not enabled to
> - wake up the system from sleep states, this attribute is empty.
> + wake up the system from sleep states, this attribute is not
> + present.
>
> What: /sys/devices/.../power/wakeup_active
> Date: September 2010
> @@ -115,7 +115,7 @@ Description:
> or 0, depending on whether or not a wakeup event associated with
> the device is being processed (1). This attribute is read-only.
> If the device is not enabled to wake up the system from sleep
> - states, this attribute is empty.
> + states, this attribute is not present.
>
> What: /sys/devices/.../power/wakeup_total_time_ms
> Date: September 2010
> @@ -125,7 +125,7 @@ Description:
> the total time of processing wakeup events associated with the
> device, in milliseconds. This attribute is read-only. If the
> device is not enabled to wake up the system from sleep states,
> - this attribute is empty.
> + this attribute is not present.
>
> What: /sys/devices/.../power/wakeup_max_time_ms
> Date: September 2010
> @@ -135,7 +135,7 @@ Description:
> the maximum time of processing a single wakeup event associated
> with the device, in milliseconds. This attribute is read-only.
> If the device is not enabled to wake up the system from sleep
> - states, this attribute is empty.
> + states, this attribute is not present.
>
> What: /sys/devices/.../power/wakeup_last_time_ms
> Date: September 2010
> @@ -146,7 +146,7 @@ Description:
> signaling the last wakeup event associated with the device, in
> milliseconds. This attribute is read-only. If the device is
> not enabled to wake up the system from sleep states, this
> - attribute is empty.
> + attribute is not present.
>
> What: /sys/devices/.../power/autosuspend_delay_ms
> Date: September 2010
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