phosphor-power-sequencer/docs/powering_on.md

3 ## Initiating a power on
6 Redfish command, or a power button on the system enclosure.
9 `org.openbmc.control.Power` D-Bus interface. The D-Bus object path is
13 The `phosphor-power-sequencer` application only supports powering on the entire
14 system. In a multiple chassis system, `phosphor-power-sequencer` does not
17 ## Determining which chassis to power on
19 In a single chassis system, `phosphor-power-sequencer` will always attempt to
20 power on the chassis.
22 In a multiple chassis system, `phosphor-power-sequencer` will only attempt to
23 power on chassis with the proper status:
30 `phosphor-power-sequencer` will set the `state` property to 1 for each chassis
34 If no chassis are in the proper status to power on, `phosphor-power-sequencer`
36 [power off](powering_off.md) the system.
43 `phosphor-power-sequencer` powers on the main (non-standby) voltage rails in a
44 chassis by toggling a named GPIO to the power sequencer device in the chassis.
47 In each chassis being powered on, the power sequencer device powers on the
50 ## Determining when power on is complete
52 When all voltage rails have been successfully powered on in a chassis, the power
53 sequencer device will set the chassis power good (pgood) signal to true.
55 `phosphor-power-sequencer` reads the chassis pgood signal from a named GPIO. For
57 [Monitoring Chassis Power Good](monitoring_chassis_pgood.md).
59 When the chassis power good signal changes to true, `phosphor-power-sequencer`
60 will set the `pgood` property to 1 on the `org.openbmc.control.Power` interface
61 for the **chassis** object path. The power on has finished for that chassis.
64 `phosphor-power-sequencer` will set the `pgood` property to 1 on the
65 `org.openbmc.control.Power` interface for the **system** object path.
75 ### Power good fault
77 When the power sequencer device is powering on the main voltage rails, one of
78 the rails may fail to power on. Similarly, after the system has powered on, one
79 of the voltage rails that had been providing power to the chassis might suddenly
80 power off.
83 [Power Good Faults](pgood_faults.md) for information on how the error is
86 ### Unable to read chassis power good signal
88 `phosphor-power-sequencer` may become unable to read the chassis power good
94 See [Monitoring Chassis Power Good](monitoring_chassis_pgood.md) for more