diff options
| author | David Brownell <david-b@pacbell.net> | 2006-08-30 14:12:48 -0700 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@suse.de> | 2006-09-25 21:08:37 -0700 |
| commit | 047bda36150d11422b2c7bacca1df324c909c0b3 (patch) | |
| tree | 3ec9e87c36f26bb945bfa8c8c4beb4c5cdfc8771 /drivers/base/power | |
| parent | 4fc0840006bf3df69dcf92397fdcaf85a542f939 (diff) | |
PM: update docs for writing .../power/state
Updates to match current code:
- Make writes to the /sys/devices/.../power/state files fail cleanly
if the device requires the irqs-off call variants.
- Fix comments describing the /sys/devices/.../power/state file writes
to match the code; the last several releases have invalidated the
previous text.
Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
Diffstat (limited to 'drivers/base/power')
| -rw-r--r-- | drivers/base/power/sysfs.c | 29 |
1 files changed, 19 insertions, 10 deletions
diff --git a/drivers/base/power/sysfs.c b/drivers/base/power/sysfs.c index 40d7242a07c..e55b3c2779e 100644 --- a/drivers/base/power/sysfs.c +++ b/drivers/base/power/sysfs.c @@ -11,18 +11,23 @@ * state - Control current power state of device * * show() returns the current power state of the device. '0' indicates - * the device is on. Other values (1-3) indicate the device is in a low + * the device is on. Other values (2) indicate the device is in some low * power state. * - * store() sets the current power state, which is an integer value - * between 0-3. If the device is on ('0'), and the value written is - * greater than 0, then the device is placed directly into the low-power - * state (via its driver's ->suspend() method). - * If the device is currently in a low-power state, and the value is 0, - * the device is powered back on (via the ->resume() method). - * If the device is in a low-power state, and a different low-power state - * is requested, the device is first resumed, then suspended into the new - * low-power state. + * store() sets the current power state, which is an integer valued + * 0, 2, or 3. Devices with bus.suspend_late(), or bus.resume_early() + * methods fail this operation; those methods couldn't be called. + * Otherwise, + * + * - If the recorded dev->power.power_state.event matches the + * target value, nothing is done. + * - If the recorded event code is nonzero, the device is reactivated + * by calling bus.resume() and/or class.resume(). + * - If the target value is nonzero, the device is suspended by + * calling class.suspend() and/or bus.suspend() with event code + * PM_EVENT_SUSPEND. + * + * This mechanism is DEPRECATED and should only be used for testing. */ static ssize_t state_show(struct device * dev, struct device_attribute *attr, char * buf) @@ -38,6 +43,10 @@ static ssize_t state_store(struct device * dev, struct device_attribute *attr, c pm_message_t state; int error = -EINVAL; + /* disallow incomplete suspend sequences */ + if (dev->bus && (dev->bus->suspend_late || dev->bus->resume_early)) + return error; + state.event = PM_EVENT_SUSPEND; /* Older apps expected to write "3" here - confused with PCI D3 */ if ((n == 1) && !strcmp(buf, "3")) |