1*971cb7fbSRafael J. WysockiWhat: /sys/devices/.../power/ 2*971cb7fbSRafael J. WysockiDate: January 2009 3*971cb7fbSRafael J. WysockiContact: Rafael J. Wysocki <rjw@sisk.pl> 4*971cb7fbSRafael J. WysockiDescription: 5*971cb7fbSRafael J. Wysocki The /sys/devices/.../power directory contains attributes 6*971cb7fbSRafael J. Wysocki allowing the user space to check and modify some power 7*971cb7fbSRafael J. Wysocki management related properties of given device. 8*971cb7fbSRafael J. Wysocki 9*971cb7fbSRafael J. WysockiWhat: /sys/devices/.../power/wakeup 10*971cb7fbSRafael J. WysockiDate: January 2009 11*971cb7fbSRafael J. WysockiContact: Rafael J. Wysocki <rjw@sisk.pl> 12*971cb7fbSRafael J. WysockiDescription: 13*971cb7fbSRafael J. Wysocki The /sys/devices/.../power/wakeup attribute allows the user 14*971cb7fbSRafael J. Wysocki space to check if the device is enabled to wake up the system 15*971cb7fbSRafael J. Wysocki from sleep states, such as the memory sleep state (suspend to 16*971cb7fbSRafael J. Wysocki RAM) and hibernation (suspend to disk), and to enable or disable 17*971cb7fbSRafael J. Wysocki it to do that as desired. 18*971cb7fbSRafael J. Wysocki 19*971cb7fbSRafael J. Wysocki Some devices support "wakeup" events, which are hardware signals 20*971cb7fbSRafael J. Wysocki used to activate the system from a sleep state. Such devices 21*971cb7fbSRafael J. Wysocki have one of the following two values for the sysfs power/wakeup 22*971cb7fbSRafael J. Wysocki file: 23*971cb7fbSRafael J. Wysocki 24*971cb7fbSRafael J. Wysocki + "enabled\n" to issue the events; 25*971cb7fbSRafael J. Wysocki + "disabled\n" not to do so; 26*971cb7fbSRafael J. Wysocki 27*971cb7fbSRafael J. Wysocki In that cases the user space can change the setting represented 28*971cb7fbSRafael J. Wysocki by the contents of this file by writing either "enabled", or 29*971cb7fbSRafael J. Wysocki "disabled" to it. 30*971cb7fbSRafael J. Wysocki 31*971cb7fbSRafael J. Wysocki For the devices that are not capable of generating system wakeup 32*971cb7fbSRafael J. Wysocki events this file contains "\n". In that cases the user space 33*971cb7fbSRafael J. Wysocki cannot modify the contents of this file and the device cannot be 34*971cb7fbSRafael J. Wysocki enabled to wake up the system. 35*971cb7fbSRafael J. Wysocki 36*971cb7fbSRafael J. WysockiWhat: /sys/devices/.../power/control 37*971cb7fbSRafael J. WysockiDate: January 2009 38*971cb7fbSRafael J. WysockiContact: Rafael J. Wysocki <rjw@sisk.pl> 39*971cb7fbSRafael J. WysockiDescription: 40*971cb7fbSRafael J. Wysocki The /sys/devices/.../power/control attribute allows the user 41*971cb7fbSRafael J. Wysocki space to control the run-time power management of the device. 42*971cb7fbSRafael J. Wysocki 43*971cb7fbSRafael J. Wysocki All devices have one of the following two values for the 44*971cb7fbSRafael J. Wysocki power/control file: 45*971cb7fbSRafael J. Wysocki 46*971cb7fbSRafael J. Wysocki + "auto\n" to allow the device to be power managed at run time; 47*971cb7fbSRafael J. Wysocki + "on\n" to prevent the device from being power managed; 48*971cb7fbSRafael J. Wysocki 49*971cb7fbSRafael J. Wysocki The default for all devices is "auto", which means that they may 50*971cb7fbSRafael J. Wysocki be subject to automatic power management, depending on their 51*971cb7fbSRafael J. Wysocki drivers. Changing this attribute to "on" prevents the driver 52*971cb7fbSRafael J. Wysocki from power managing the device at run time. Doing that while 53*971cb7fbSRafael J. Wysocki the device is suspended causes it to be woken up. 54