[PATCH v4 0/4] regulator: qcom-rpmh: Add support for off-on-delay and debounce-delay

[Jishnu Prakash <jishnu.prakash@oss.qualcomm.com>]

This series adds support for two related delay properties for the Qualcomm
RPMh regulator driver: `regulator-off-on-delay-us` (enforces a minimum
physical off-time before re-enable) and `qcom,regulator-off-debounce-delay-us`
(defers sending a disable request to RPMh so quick disable/enable bounces
never reach the hardware).

Motivation:
On the Lenovo Yoga Slim 7x (Snapdragon X Elite), the camera regulators
(LDO1, LDO3, LDO7) have large bulk capacitors and rely on passive discharge.
When these regulators are disabled, the voltage decays very slowly. If
re-enabled too quickly, the sensor experiences a brownout and fails to
initialize. This can be prevented by specifying a minimum off-time.

Separately, some consumers rapidly toggle a regulator off and on again,
for example, a driver that disables its supply on -EPROBE_DEFER and
re-enables it on the next probe attempt. Sending the disable vote to RPMh
immediately in this case causes needless power cycling, so
qcom,regulator-off-debounce-delay-us lets this be deferred and canceled
if a quick re-enable follows.

Signed-off-by: Jishnu Prakash <jishnu.prakash@oss.qualcomm.com>
---
Changes in v4:
- Taking over upstreaming this series from Saikiran.
- Made the binding change for `regulator-off-on-delay-us` in
  Documentation/devicetree/bindings/regulator/regulator.yaml instead of
  Documentation/devicetree/bindings/regulator/qcom,rpmh-regulator.yaml,
  as this property seems better suited to be a generic one.
- Added new `qcom,regulator-off-debounce-delay-us` property and driver
  support for deferring the RPMh disable request to implement Mark's
  suggestion.
- Rebased to Linux 7.3-rc5.
- Link to v3: https://patch.msgid.link/20260127190211.14312-1-bjsaikiran@gmail.com

Changes in v3:
- Added Patch 1/2: Update DT bindings to allow `regulator-off-on-delay-us`
  for `qcom,rpmh-regulator` (Requested by Mark Brown).
- Updated Patch 2/2: Refined commit message to explicitly mention the
  passive discharge and bulk capacitor mechanism on the Yoga Slim 7x
  (Requested by Mark Brown).

Changes in v2:
- Moved the motivation/context from the cover letter into the commit
  message of the driver patch.

---
Jishnu Prakash (3):
      regulator: dt-bindings: Add 'regulator-off-on-delay-us' property
      regulator: dt-bindings: qcom,rpmh-regulator: Add debounce delay property
      regulator: qcom-rpmh: Add debounce delay before disabling regulator

Saikiran (1):
      regulator: qcom-rpmh: Add support for regulator-off-on-delay-us

 .../bindings/regulator/qcom,rpmh-regulator.yaml    |  18 ++++
 .../devicetree/bindings/regulator/regulator.yaml   |   5 +
 drivers/regulator/qcom-rpmh-regulator.c            | 113 ++++++++++++++++++++-
 3 files changed, 132 insertions(+), 4 deletions(-)
---
base-commit: 72d3fcf802c45d00b300f25b848a93c3a2bd7c7e
change-id: 20260910-regulator-off-on-delay-2c86cb8f3eb8

Best regards,
--  
Jishnu Prakash <jishnu.prakash@oss.qualcomm.com>