Re: [PATCH v5 1/7] regulator: core: Add "enable and wait" functions

On Tue, Aug 25, 2026 at 12:33 PM Chen-Yu Tsai [off-list ref] wrote:

In device power sequencing and initialization use cases, it is common
for the driver to enable the regulator and then wait for a certain
period of time to pass before continuing.

In cases where the regulator supply is always on, or has been turned on
or left on by another consumer, the driver could shorten the delay or
skip it altogether, provided that enough time has already passed since
the regulator was _actually_ turned on.

Tracking this requires support from the regulator core. Introduce a
"last turned on" timestamp field to the regulator device, and "enable
and wait" functions to the single and bulk regulator consumer APIs.
The existing "enable without wait" functions are then converted to
macros that expand to the new functions.

The timestamp is updated each time the regulator is actually turned on.
For regulators left on by hardware default or by firmware, the core will
set the timestamp if it detects it was left on and its supply (and their
supply, and so on) is on as well. This is unfortunately best effort
only. The core can only assume a dangling regulator (one without a
supply) has power. This also applies to the dummy regulator.

Signed-off-by: Chen-Yu Tsai <wenst@chromium.org>
---
Changes since v4:
- Try to update last_on timestamp for regulators that were left on

Sashiko flaged a few issues with the changes:

- _regulator_is_enabled() called and subsequent timestamp update
  without lock
- bulk consumer wait_us incorrectly assigned
- _regulator_is_enabled() could return an error

Will fix and send a new version. I probably should get a local AI review
working first.


ChenYu