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- What: /sys/bus/i2c/devices/.../bd9571mwv-regulator.*.auto/backup_mode
- Date: Jul 2018
- KernelVersion: 4.19
- Contact: Geert Uytterhoeven <[email protected]>
- Description: Read/write the current state of DDR Backup Mode, which controls
- if DDR power rails will be kept powered during system suspend.
- ("on"/"1" = enabled, "off"/"0" = disabled).
- Two types of power switches (or control signals) can be used:
- A. With a momentary power switch (or pulse signal), DDR
- Backup Mode is enabled by default when available, as the
- PMIC will be configured only during system suspend.
- B. With a toggle power switch (or level signal), the
- following steps must be followed exactly:
- 1. Configure PMIC for backup mode, to change the role of
- the accessory power switch from a power switch to a
- wake-up switch,
- 2. Switch accessory power switch off, to prepare for
- system suspend, which is a manual step not controlled
- by software,
- 3. Suspend system,
- 4. Switch accessory power switch on, to resume the
- system.
- DDR Backup Mode must be explicitly enabled by the user,
- to invoke step 1.
- See also Documentation/devicetree/bindings/mfd/rohm,bd9571mwv.yaml.
- Users: User space applications for embedded boards equipped with a
- BD9571MWV PMIC.
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