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1What: /sys/bus/i2c/devices/.../bd9571mwv-regulator.*.auto/backup_mode2Date: Jul 20183KernelVersion: 4.194Contact: Geert Uytterhoeven <geert+renesas@glider.be>5Description: Read/write the current state of DDR Backup Mode, which controls6 if DDR power rails will be kept powered during system suspend.7 ("on"/"1" = enabled, "off"/"0" = disabled).8 Two types of power switches (or control signals) can be used:9 10 A. With a momentary power switch (or pulse signal), DDR11 Backup Mode is enabled by default when available, as the12 PMIC will be configured only during system suspend.13 B. With a toggle power switch (or level signal), the14 following steps must be followed exactly:15 16 1. Configure PMIC for backup mode, to change the role of17 the accessory power switch from a power switch to a18 wake-up switch,19 2. Switch accessory power switch off, to prepare for20 system suspend, which is a manual step not controlled21 by software,22 3. Suspend system,23 4. Switch accessory power switch on, to resume the24 system.25 26 DDR Backup Mode must be explicitly enabled by the user,27 to invoke step 1.28 29 See also Documentation/devicetree/bindings/mfd/rohm,bd9571mwv.yaml.30Users: User space applications for embedded boards equipped with a31 BD9571MWV PMIC.32