1 What: /sys/bus/i2c/devices/.../bd9571mwv-regulator.*.auto/backup_mode
2 Date: Jul 2018
3 KernelVersion: 4.19
4 Contact: Geert Uytterhoeven <geert+renesas@glider.be>
5 Description: Read/write the current state of DDR Backup Mode, which controls
6 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), DDR
11 Backup Mode is enabled by default when available, as the
12 PMIC will be configured only during system suspend.
13 B. With a toggle power switch (or level signal), the
14 following steps must be followed exactly:
15
16 1. Configure PMIC for backup mode, to change the role of
17 the accessory power switch from a power switch to a
18 wake-up switch,
19 2. Switch accessory power switch off, to prepare for
20 system suspend, which is a manual step not controlled
21 by software,
22 3. Suspend system,
23 4. Switch accessory power switch on, to resume the
24 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.
30 Users: User space applications for embedded boards equipped with a
31 BD9571MWV PMIC.
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