[PATCH v3 1/3] iio: imu: inv_mpu6050: fix unbalanced regulator_disable calls, when probe fails

[Andrey Skvortsov]

During a probe functions after all regulators are enabled, runtime pm
is enabled. Before probe function finishes, runtime pm triggers and
disables vddio regulator. When probe function fails after that,
inv_mpu_core_disable_regulator_action tries to disable already
disabled by runtime pm vddio regulator causing following backtrace:

  inv-mpu6050-i2c 1-0068: trigger probe fail -19
  WARNING: drivers/regulator/core.c:3244 at _regulator_disable+0x2ac/0x600
  Call trace:
   _regulator_disable+0x2ac/0x600 (P)
   regulator_disable+0xac/0x148
   inv_mpu_core_disable_regulator_vddio_action+0x3c/0xb0 [inv_mpu6050]
   devm_action_release+0x4c/0x88
   release_nodes+0xd8/0x178
   devres_release_group+0x214/0x3c8
   i2c_device_probe+0x6fc/0x9b0
  ...
  inv-mpu6050-i2c 1-0068: Failed to disable vddio regulator: -5

vddio state is handled in two places: pm_runtime and
inv_mpu_core_disable_regulator_vddio_action devm action.
inv_mpu_core_disable_regulator_vddio_action has to check, whether
regulator is disabled by pm_runtime already. But this information is
available only after pm_runtime state is initialized by
pm_runtime_set_active during a probe. So
inv_mpu_core_disable_regulator_vddio_action has to be called only
after pm_runtime is properly initialized. To handle cases, when probe
fails before pm_runtime is enabled, explicitly disable regulators
in error paths.

Signed-off-by: Andrey Skvortsov <andrej.skvortzov@xxxxxxxxx>
Fixes: 07c12b1c007c ("iio: imu: mpu6050: add support for regulator framework")
---

Changes in v3:
 - make patch to be the first patch of the patchset for easier backporting
 - update commit message to fix Andy's comment
 - don't move pm_runtime_set_active from pm_runtime initialization,
   move activation of inv_mpu_core_disable_regulator_action instead

Changes in v2:
 - minimize call trace in commit message
 - include specific driver name in patch subject

 drivers/iio/imu/inv_mpu6050/inv_mpu_core.c | 25 ++++++++++++----------
 1 file changed, 14 insertions(+), 11 deletions(-)

diff --git a/drivers/iio/imu/inv_mpu6050/inv_mpu_core.c b/drivers/iio/imu/inv_mpu6050/inv_mpu_core.c
index 5796896d54cd8..49fdf33adec99 100644
--- a/drivers/iio/imu/inv_mpu6050/inv_mpu_core.c
+++ b/drivers/iio/imu/inv_mpu6050/inv_mpu_core.c
@@ -1862,6 +1862,7 @@ static int inv_mpu_core_disable_regulator_vddio(struct inv_mpu6050_state *st)
 static void inv_mpu_core_disable_regulator_action(void *_data)
 {
 	struct inv_mpu6050_state *st = _data;
+	struct device *dev = regmap_get_device(st->map);
 	int result;
 
 	result = regulator_disable(st->vdd_supply);
@@ -1869,7 +1870,8 @@ static void inv_mpu_core_disable_regulator_action(void *_data)
 		dev_err(regmap_get_device(st->map),
 			"Failed to disable vdd regulator: %d\n", result);
 
-	inv_mpu_core_disable_regulator_vddio(st);
+	if (!pm_runtime_status_suspended(dev))
+		inv_mpu_core_disable_regulator_vddio(st);
 }
 
 static void inv_mpu_pm_disable(void *data)
@@ -1976,23 +1978,15 @@ int inv_mpu_core_probe(struct regmap *regmap, int irq, const char *name,
 		return result;
 	}
 
-	result = devm_add_action_or_reset(dev, inv_mpu_core_disable_regulator_action,
-				 st);
-	if (result) {
-		dev_err(dev, "Failed to setup regulator cleanup action %d\n",
-			result);
-		return result;
-	}
-
 	/* fill magnetometer orientation */
 	result = inv_mpu_magn_set_orient(st);
 	if (result)
-		return result;
+		goto error_vddio_off;
 
 	/* power is turned on inside check chip type*/
 	result = inv_check_and_setup_chip(st);
 	if (result)
-		return result;
+		goto error_vddio_off;
 
 	result = inv_mpu6050_init_config(indio_dev);
 	if (result) {
@@ -2018,6 +2012,12 @@ int inv_mpu_core_probe(struct regmap *regmap, int irq, const char *name,
 	result = pm_runtime_set_active(dev);
 	if (result)
 		goto error_power_off;
+
+	result = devm_add_action_or_reset(dev, inv_mpu_core_disable_regulator_action,
+					  st);
+	if (result)
+		return dev_err_probe(dev, result,
+				     "Failed to setup regulator cleanup action\n");
 	pm_runtime_get_noresume(dev);
 	pm_runtime_enable(dev);
 	pm_runtime_set_autosuspend_delay(dev, INV_MPU6050_SUSPEND_DELAY_MS);
@@ -2114,6 +2114,9 @@ int inv_mpu_core_probe(struct regmap *regmap, int irq, const char *name,
 
 error_power_off:
 	inv_mpu6050_set_power_itg(st, false);
+error_vddio_off:
+	inv_mpu_core_disable_regulator_vddio(st);
+	regulator_disable(st->vdd_supply);
 	return result;
 }
 EXPORT_SYMBOL_NS_GPL(inv_mpu_core_probe, "IIO_MPU6050");
-- 
2.53.0