On read, the actual state the device is in is reported (as
recorded in the pm_message_t::state field), instead of just
"0" or "2" (which roughly map to "on" and "off"). If the
device is suspended, but the state is "0", then report
PM_STATE_OFF (defined as INT_MAX).
On write, pass the value that the user wrote to the device/
bus suspend method (via the pm_message_t::state field), so
that the device can enter the state specified by the user
process.
This retains the semantics of treating any non-zero state
request as a suspend request, setting the /event field to
PM_EVENT_SUSPEND. A value of 0 gets an .event field set to
PM_EVENT_ON.
Previously, the file interface was changed to filter all
values except "0", "2", and "3". This patch removes that
artificial filtering to let the bus/device drivers decide
what values are relevant for them, and returns the file to
its originally designed interface - to allow a user process
to place a device in the specified state.
Signed-off-by: Patrick Mochel <mochel@xxxxxxxxxxxxxxx>
---
drivers/base/power/sysfs.c | 66 ++++++++++++++++++++++++++------------------
1 files changed, 39 insertions(+), 27 deletions(-)
applies-to: 11a0502281f83482175ce71b583059b04cdef8ad
791cab449feafe0e35a7345502c2d2e26dc51d88
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
