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Commit 047bda36 authored by David Brownell's avatar David Brownell Committed by Greg Kroah-Hartman
Browse files

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: default avatarDavid Brownell <dbrownell@users.sourceforge.net>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@suse.de>
parent 4fc08400

drivers/base/power/sysfs.c

+19 −10
Original line number Diff line number Diff line
@@ -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"))