linux-kernel - [PATCH] regulator: core: disable supply if enabling main regulator fails

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Message-Id: <20251107-regulator-disable-supply-v1-1-c95f0536f1b5@gmail.com>
Date: Fri, 07 Nov 2025 18:10:08 +0100
From: Gabor Juhos <j4g8y7@...il.com>
To: Liam Girdwood <lgirdwood@...il.com>, Mark Brown <broonie@...nel.org>, 
 Douglas Anderson <dianders@...omium.org>
Cc: linux-kernel@...r.kernel.org, Gabor Juhos <j4g8y7@...il.com>
Subject: [PATCH] regulator: core: disable supply if enabling main regulator
 fails

For 'always-on' and 'boot-on' regulators, the set_machine_constraints()
may enable supply before enabling the main regulator, however if the
latter fails, the function returns with an error but the supply remains
enabled.

When this happens, the regulator_register() function continues on the
error path where it puts the supply regulator. Since enabling the supply
is not balanced with a disable call, a warning similar to the following
gets issued from _regulator_put():

    [    1.603889] WARNING: CPU: 2 PID: 44 at _regulator_put+0x8c/0xa0
    [    1.603908] Modules linked in:
    [    1.603926] CPU: 2 UID: 0 PID: 44 Comm: kworker/u16:3 Not tainted 6.18.0-rc4 #0 NONE
    [    1.603938] Hardware name: Qualcomm Technologies, Inc. IPQ9574/AP-AL02-C7 (DT)
    [    1.603945] Workqueue: async async_run_entry_fn
    [    1.603958] pstate: 60400005 (nZCv daif +PAN -UAO -TCO -DIT -SSBS BTYPE=--)
    [    1.603967] pc : _regulator_put+0x8c/0xa0
    [    1.603976] lr : _regulator_put+0x7c/0xa0
    ...
    [    1.604140] Call trace:
    [    1.604145]  _regulator_put+0x8c/0xa0 (P)
    [    1.604156]  regulator_register+0x2ec/0xbf0
    [    1.604166]  devm_regulator_register+0x60/0xb0
    [    1.604178]  rpm_reg_probe+0x120/0x208
    [    1.604187]  platform_probe+0x64/0xa8
    ...

In order to avoid this, change the set_machine_constraints() function to
disable the supply if enabling the main regulator fails.

Fixes: 05f224ca6693 ("regulator: core: Clean enabling always-on regulators + their supplies")
Signed-off-by: Gabor Juhos <j4g8y7@...il.com>
---
 drivers/regulator/core.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/drivers/regulator/core.c b/drivers/regulator/core.c
index dd7b10e768c06c83d2a4fb5dfd0fce8d796c9185..fc93612f4ec0c3ea3a68db5611abcf9d538c8010 100644
--- a/drivers/regulator/core.c
+++ b/drivers/regulator/core.c
@@ -1618,6 +1618,8 @@ static int set_machine_constraints(struct regulator_dev *rdev)
 	 * 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.
 		 */
@@ -1637,11 +1639,14 @@ static int set_machine_constraints(struct regulator_dev *rdev)
 				rdev->supply = NULL;
 				return ret;
 			}
+			supply_enabled = true;
 		}
 
 		ret = _regulator_do_enable(rdev);
 		if (ret < 0 && ret != -EINVAL) {
 			rdev_err(rdev, "failed to enable: %pe\n", ERR_PTR(ret));
+			if (supply_enabled)
+				regulator_disable(rdev->supply);
 			return ret;
 		}
 

---
base-commit: 636f4618b1cd96f6b5a2b8c7c4f665c8533ecf13
change-id: 20251107-regulator-disable-supply-405e47a4c565

Best regards,
-- 
Gabor Juhos <j4g8y7@...il.com>