[PATCH/RFC 4/5] regulator: bd9571mwv: Add support for backup mode

On Wed, Oct 18, 2017 at 01:19:08PM +0200, Geert Uytterhoeven wrote:

On Wed, Oct 18, 2017 at 1:02 PM, Mark Brown [off-list ref] wrote:

quoted

On Tue, Oct 10, 2017 at 05:26:17PM +0200, Geert Uytterhoeven wrote:

quoted

quoted

Backup mode is not enabled automatically, as e.g. on Renesas
Salvator-X(S) boards enabling backup mode changes the role of the ACC
switch from a power switch to a wake-up switch.  Hence enabling it
prevents the board from being powered off using the ACC switch, which
may confuse the user.

quoted

This sounds an awful lot like the standard power/wakeup, though the
power change is a bit unexpected there.  I'm also wondering if it makes
sense to just only enable the wakeup mode when suspending which
preserves the power off functionality while also keeping the wakeup
support.

The ACC switch is not a momentary switch (push button), but a toggle
switch with two positions.
Hence you cannot enable wakeup mode while suspending, as the proper
system suspend/resume procedure is:
  1. Enable backup mode in the PMIC,
  2. Switch ACC off (no-op as backup mode has been enabled),
  3. Suspend to RAM (PSCI suspend) => system suspends,
  4. Switch ACC on => system wakes up.
If you would combine steps 1 and 3, you can no longer do step 2 in between.

Yes, it's complicated :-(

I'm confused, I thought this was a physical switch but that's talking
about this as something software controlled (at least in step 2)?
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