phosphor-power-sequencer/docs/powering_on.md

1 # Powering On
3 ## Initiating a power on
5 The system can be powered on by several methods, such as the `obmcutil` tool, a
6 Redfish command, or a power button on the system enclosure.
8 Whichever method is used, it sets the `state` property to 1 on the
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
15 support powering on individual chassis independent of the rest of the system.
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:
25 - `Present` property is true
26 - `Enabled` property is true (if interface exists)
27 - `Available` property is true (if interface exists)
28 - `Status` property is `Good` (if interface exists)
30 `phosphor-power-sequencer` will set the `state` property to 1 for each chassis
31 that is being powered on. It will set `state` to 0 for each chassis not being
32 powered on.
34 If no chassis are in the proper status to power on, `phosphor-power-sequencer`
35 will log an error. `phosphor-chassis-state-manager` will
36 [power off](powering_off.md) the system.
38 See [Chassis Status](chassis_status.md) for more information on these
41 ## Powering on the voltage rails
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.
63 When all chassis that were being powered on have finished,
64 `phosphor-power-sequencer` will set the `pgood` property to 1 on the
65 `org.openbmc.control.Power` interface for the **system** object path.
67 See [Chassis Status](chassis_status.md) for more information on the `pgood`
70 After all chassis have powered on, the rest of the boot process continues. The
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
91 - Hardware communication problems.
92 - The `Available` property of the chassis changes to false.
94 See [Monitoring Chassis Power Good](monitoring_chassis_pgood.md) for more
95 information on how the error is handled.