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authorRafael J. Wysocki <rjw@sisk.pl>2010-01-23 22:23:32 +0100
committerRafael J. Wysocki <rjw@sisk.pl>2010-02-26 20:39:09 +0100
commit5af84b82701a96be4b033aaa51d86c72e2ded061 (patch)
treeac5751c7d2e9c17bf41dabdbeba964a05f09af18 /include
parent8cc6b39ff36b4bbce2d7471da088df122b0e9033 (diff)
PM: Asynchronous suspend and resume of devices
Theoretically, the total time of system sleep transitions (suspend to RAM, hibernation) can be reduced by running suspend and resume callbacks of device drivers in parallel with each other. However, there are dependencies between devices such that we're not allowed to suspend the parent of a device before suspending the device itself. Analogously, we're not allowed to resume a device before resuming its parent. The most straightforward way to take these dependencies into accout is to start the async threads used for suspending and resuming devices at the core level, so that async_schedule() is called for each suspend and resume callback supposed to be executed asynchronously. For this purpose, introduce a new device flag, power.async_suspend, used to mark the devices whose suspend and resume callbacks are to be executed asynchronously (ie. in parallel with the main suspend/resume thread and possibly in parallel with each other) and helper function device_enable_async_suspend() allowing one to set power.async_suspend for given device (power.async_suspend is unset by default for all devices). For each device with the power.async_suspend flag set the PM core will use async_schedule() to execute its suspend and resume callbacks. The async threads started for different devices as a result of calling async_schedule() are synchronized with each other and with the main suspend/resume thread with the help of completions, in the following way: (1) There is a completion, power.completion, for each device object. (2) Each device's completion is reset before calling async_schedule() for the device or, in the case of devices with the power.async_suspend flags unset, before executing the device's suspend and resume callbacks. (3) During suspend, right before running the bus type, device type and device class suspend callbacks for the device, the PM core waits for the completions of all the device's children to be completed. (4) During resume, right before running the bus type, device type and device class resume callbacks for the device, the PM core waits for the completion of the device's parent to be completed. (5) The PM core completes power.completion for each device right after the bus type, device type and device class suspend (or resume) callbacks executed for the device have returned. Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
Diffstat (limited to 'include')
-rw-r--r--include/linux/device.h6
-rw-r--r--include/linux/pm.h3
-rw-r--r--include/linux/resume-trace.h7
3 files changed, 16 insertions, 0 deletions
diff --git a/include/linux/device.h b/include/linux/device.h
index a62799f2ab0..70adc5f3f50 100644
--- a/include/linux/device.h
+++ b/include/linux/device.h
@@ -472,6 +472,12 @@ static inline int device_is_registered(struct device *dev)
return dev->kobj.state_in_sysfs;
}
+static inline void device_enable_async_suspend(struct device *dev)
+{
+ if (dev->power.status == DPM_ON)
+ dev->power.async_suspend = true;
+}
+
void driver_init(void);
/*
diff --git a/include/linux/pm.h b/include/linux/pm.h
index 25b1eca8049..9c16cd20fc9 100644
--- a/include/linux/pm.h
+++ b/include/linux/pm.h
@@ -26,6 +26,7 @@
#include <linux/spinlock.h>
#include <linux/wait.h>
#include <linux/timer.h>
+#include <linux/completion.h>
/*
* Callbacks for platform drivers to implement.
@@ -412,9 +413,11 @@ struct dev_pm_info {
pm_message_t power_state;
unsigned int can_wakeup:1;
unsigned int should_wakeup:1;
+ unsigned async_suspend:1;
enum dpm_state status; /* Owned by the PM core */
#ifdef CONFIG_PM_SLEEP
struct list_head entry;
+ struct completion completion;
#endif
#ifdef CONFIG_PM_RUNTIME
struct timer_list suspend_timer;
diff --git a/include/linux/resume-trace.h b/include/linux/resume-trace.h
index c9ba2fdf807..bc8c3881c72 100644
--- a/include/linux/resume-trace.h
+++ b/include/linux/resume-trace.h
@@ -6,6 +6,11 @@
extern int pm_trace_enabled;
+static inline int pm_trace_is_enabled(void)
+{
+ return pm_trace_enabled;
+}
+
struct device;
extern void set_trace_device(struct device *);
extern void generate_resume_trace(const void *tracedata, unsigned int user);
@@ -17,6 +22,8 @@ extern void generate_resume_trace(const void *tracedata, unsigned int user);
#else
+static inline int pm_trace_is_enabled(void) { return 0; }
+
#define TRACE_DEVICE(dev) do { } while (0)
#define TRACE_RESUME(dev) do { } while (0)