[PATCH 6.18 196/641] regulator: core: move supply check earlier in set_machine_constraints()

Greg Kroah-Hartman
2026-02-25T01:45:30Z

6.18-stable review patch. If anyone has any objections, please let me know.

------------------

From: André Draszik <andre.draszik@linaro.org>

[ Upstream commit 86a8eeb0e913f4b6a55dabba5122098d4e805e55 ]

Since commit 98e48cd9283d ("regulator: core: resolve supply for
boot-on/always-on regulators"), set_machine_constraints() can return
-EPROBE_DEFER very late, after it has done a lot of work and
configuration of the regulator.

This means that configuration will happen multiple times for no
benefit in that case. Furthermore, this can lead to timing-dependent
voltage glitches as mentioned e.g. in commit 8a866d527ac0 ("regulator:
core: Resolve supply name earlier to prevent double-init").

We can know that it's going to fail very early, in particular before
going through the complete regulator configuration by moving some code
around a little.

Do so to avoid re-configuring the regulator multiple times, also
avoiding the voltage glitches if we can.

Fixes: 98e48cd9283d ("regulator: core: resolve supply for boot-on/always-on regulators")
Signed-off-by: André Draszik <andre.draszik@linaro.org>
Link: https://patch.msgid.link/20260109-regulators-defer-v2-3-1a25dc968e60@linaro.org
Signed-off-by: Mark Brown <broonie@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/regulator/core.c | 55 ++++++++++++++++++++++------------------
1 file changed, 30 insertions(+), 25 deletions(-)

diff --git a/drivers/regulator/core.c b/drivers/regulator/core.c
index b38b087eccfd7..17c60d9547dc5 100644
--- a/drivers/regulator/core.c
+++ b/drivers/regulator/core.c
@@ -1431,6 +1431,33 @@ static int set_machine_constraints(struct regulator_dev *rdev)
int ret = 0;
const struct regulator_ops *ops = rdev->desc->ops;

+ /*
+ * If there is no mechanism for controlling the regulator then
+ * flag it as always_on so we don't end up duplicating checks
+ * for this so much. Note that we could control the state of
+ * a supply to control the output on a regulator that has no
+ * direct control.
+ */
+ if (!rdev->ena_pin && !ops->enable) {
+ if (rdev->supply_name && !rdev->supply)
+ return -EPROBE_DEFER;
+
+ if (rdev->supply)
+ rdev->constraints->always_on =
+ rdev->supply->rdev->constraints->always_on;
+ else
+ rdev->constraints->always_on = true;
+ }
+
+ /*
+ * If we want to enable this regulator, make sure that we know the
+ * supplying regulator.
+ */
+ if (rdev->constraints->always_on || rdev->constraints->boot_on) {
+ if (rdev->supply_name && !rdev->supply)
+ return -EPROBE_DEFER;
+ }
+
ret = machine_constraints_voltage(rdev, rdev->constraints);
if (ret != 0)
return ret;
@@ -1596,37 +1623,15 @@ static int set_machine_constraints(struct regulator_dev *rdev)
}
}

- /*
- * If there is no mechanism for controlling the regulator then
- * flag it as always_on so we don't end up duplicating checks
- * for this so much. Note that we could control the state of
- * a supply to control the output on a regulator that has no
- * direct control.
- */
- if (!rdev->ena_pin && !ops->enable) {
- if (rdev->supply_name && !rdev->supply)
- return -EPROBE_DEFER;
-
- if (rdev->supply)
- rdev->constraints->always_on =
- rdev->supply->rdev->constraints->always_on;
- else
- rdev->constraints->always_on = true;
- }
-
/* If the constraints say the regulator should be on at this point
* and we have control then make sure it is enabled.
*/
if (rdev->constraints->always_on || rdev->constraints->boot_on) {
bool supply_enabled = false;

- /* If we want to enable this regulator, make sure that we know
- * the supplying regulator.
- */
- if (rdev->supply_name && !rdev->supply)
- return -EPROBE_DEFER;
-
- /* If supplying regulator has already been enabled,
+ /* We have ensured a potential supply has been resolved above.
+ *
+ * If supplying regulator has already been enabled,
* it's not intended to have use_count increment
* when rdev is only boot-on.
*/
--
2.51.0