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Message-Id: <201101150108.45657.rjw@sisk.pl>
Date: Sat, 15 Jan 2011 01:08:45 +0100
From: "Rafael J. Wysocki" <rjw@...k.pl>
To: Alan Stern <stern@...land.harvard.edu>
Cc: "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 Friday, January 14, 2011, Alan Stern wrote:
> On Fri, 14 Jan 2011, Rafael J. Wysocki wrote:
...
> ...
>
> > 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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