[PATCH 3/5] [pm] Respect the actual device power states in sysfs interface

Patrick Mochel
2006-02-18T02:03:40Z

[-- Attachment #1: Type: TEXT/PLAIN, Size: 4431 bytes --]

Fix the per-device state file to respect the actual state that
is reported by the device, or written to the file.

Using the struct pm_message::state field:

On read, report the actual state the device is in by looking at the
struct pm_message::state field (instead of just "0" or "2"). If the
device is suspended, but the state is "0", then report PM_STATE_OFF
(defined as INT_MAX).

On write, assume that the value passed in is the state that the
user wants the device to enter. Set the struct pm_message::state
field to that value.
- When (state != 0), assume a suspend request, and always set the
event field to PM_EVENT_SUSPEND
- When (state == 0), assume a resume request.

[ Previously, only values "0", "2", and "3" were accepted, and the
actual value passed was silently dropped. ]

Update the comments so they match the functionality.

Signed-off-by: Patrick Mochel <mochel@linux.intel.com>

---

drivers/base/power/sysfs.c | 66 ++++++++++++++++++++++++++------------------
1 files changed, 39 insertions(+), 27 deletions(-)

applies-to: c5da8670faf610adc21e38c9d2da5330e9232a37
0f3eb786f769badd9044117c2976f829d66dec73
diff --git a/drivers/base/power/sysfs.c b/drivers/base/power/sysfs.c
index 40d7242..308baff 100644
--- a/drivers/base/power/sysfs.c
+++ b/drivers/base/power/sysfs.c
@@ -7,50 +7,62 @@
#include "power.h"

+#define PM_STATE_OFF INT_MAX
+
/**
* 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
* 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.
+ * A value of INT_MAX (0x0fffffff) indicates that the device is off - it is
+ * suspended, but the actual state is unknown (for devices and buses that only
+ * support "on" and "off").
+ *
+ * store() takes an integer value and changes the current power state of the
+ * device. If this value is 0, the device is resumed - a PM message with event
+ * type PM_EVENT_ON, and a state of 0 is passed to dpm_runtime_resume().
+ * Otherwise, the device is suspended. A PM message with event type
+ * PM_EVENT_SUSPEND is passed to the device, with the state being the value
+ * written to this file.
+ *
+ * The meaning of the integer value states are bus and/or device specific, with
+ * the exception of 0 - that always means "on".
+ * The core will not do any further interpretation of the values. It is up to
+ * the bus and/or device drivers to both document and check the values that are
+ * read and written from this file.
+ * For buses and devices that only support "on" and "off", any non-zero number
+ * can be used to indicate "off".
*/

static ssize_t state_show(struct device * dev, struct device_attribute *attr, char * buf)
{
- if (dev->power.power_state.event)
- return sprintf(buf, "2\n");
- else
- return sprintf(buf, "0\n");
+ u32 state = 0;
+
+ if (dev->power.power_state.event == PM_EVENT_SUSPEND) {
+ state = dev->power.power_state.state;
+ if (!state)
+ state = PM_STATE_OFF;
+ }
+ return sprintf(buf, "%x\n", dev->power.power_state.state);
}

static ssize_t state_store(struct device * dev, struct device_attribute *attr, const char * buf, size_t n)
{
- pm_message_t state;
- int error = -EINVAL;
+ pm_message_t msg = {
+ .event = PM_EVENT_SUSPEND,
+ };
+ char * rest;
+ int error = 0;

- state.event = PM_EVENT_SUSPEND;
- /* Older apps expected to write "3" here - confused with PCI D3 */
- if ((n == 1) && !strcmp(buf, "3"))
- error = dpm_runtime_suspend(dev, state);
-
- if ((n == 1) && !strcmp(buf, "2"))
- error = dpm_runtime_suspend(dev, state);
+ msg.state = simple_strtoul(buf, &rest, 0);
+ if (*rest)
+ return -EINVAL;

- if ((n == 1) && !strcmp(buf, "0")) {
+ if (msg.state)
+ error = dpm_runtime_suspend(dev, msg);
+ else
dpm_runtime_resume(dev);
- error = 0;
- }
-
return error ? error : n;
}

---
0.99.9.GIT