NO-INVOLUNTARY-POWER-CYCLES(9P) Kernel Properties for Drivers


NAME


no-involuntary-power-cycles - device property to prevent involuntary
power cycles

DESCRIPTION


A device that might be damaged by power cycles should export the boolean
(zero length) property no-involuntary-power-cycles to notify the system
that all power cycles for the device must be under the control of the
device driver.


The presence of this property prevents power from being removed from a
device or any ancestor of the device while the device driver is detached,
unless the device was voluntarily powered off as a result of the device
driver calling pm_lower_power(9F).


The presence of no-involuntary-power-cycles also forces attachment of the
device driver during a CPR suspend operation and prevents the suspend
from taking place, unless the device driver returns DDI_SUCCESS when its
detach(9E) entry point is called with DDI_SUSPEND.


The presence of no-involuntary-power-cycles does not prevent the system
from being powered off due to a halt(1M) or uadmin(1M) invocation, except
for CPR suspend.


This property can be exported by a device that is not power manageable,
in which case power is not removed from the device or from any of its
ancestors, even when the driver for the device and the drivers for its
ancestors are detached.

EXAMPLES


Example 1: Use of Property in Driver's Configuration File




The following is an example of a no-involuntary-power-cycles entry in a
driver's .conf file:


no-involuntary-power-cycles=1;
...


Example 2: Use of Property in attach() Function




The following is an example of how the preceding .conf file entry would
be implemented in the attach(9E) function of a driver:


xxattach(dev_info_t *dip, ddi_attach_cmd_t cmd)
{
...
if (ddi_prop_create(DDI_DEV_T_NONE, dip, DDI_PROP_CANSLEEP,
"no-involuntary-power-cycles", NULL, 0) != DDI_PROP_SUCCESS)
goto failed;
...
}


ATTRIBUTES


See attributes(5) for descriptions of the following attributes:


+--------------------+-----------------+
| ATTRIBUTE TYPE | ATTRIBUTE VALUE |
+--------------------+-----------------+
|Interface stability | Committed |
+--------------------+-----------------+

SEE ALSO


attributes(5), pm(7D), attach(9E), detach(9E), ddi_prop_create(9F)


Writing Device Drivers


March 22, 2001 NO-INVOLUNTARY-POWER-CYCLES(9P)