[PATCH] iio: imu: fix unbalanced regulator_disable calls, when probe fails

[Andrey Skvortsov <andrej.skvortzov@gmail.com>]

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
 ------------[ cut here ]------------
 unbalanced disables a for vcc-dsi-sensor
 WARNING: drivers/regulator/core.c:3244 at _regulator_disable+0x118/0x260, CPU#3: (udev-worker)/357
 Call trace:
  _regulator_disable+0x118/0x260 (P)
  regulator_disable+0x50/0xa0
  inv_mpu_core_disable_regulator_action+0x30/0xa0 [inv_mpu6050]
  devm_action_release+0x1c/0x30
  release_nodes+0x6c/0xa8
  devres_release_group+0x158/0x1a0
  i2c_device_probe+0x33c/0x3a0
  really_probe+0xc8/0x3f0
  __driver_probe_device+0x88/0x170
  driver_probe_device+0x48/0x130
  __driver_attach+0x10c/0x260
  bus_for_each_dev+0x84/0xf0
  driver_attach+0x2c/0x40
  bus_add_driver+0x124/0x258
  driver_register+0x70/0x138
  i2c_register_driver+0x50/0xe8
  inv_mpu_driver_init+0x28/0xfb8 [inv_mpu6050_i2c]
  do_one_initcall+0x5c/0x478
  do_init_module+0x5c/0x268
  load_module+0x1d04/0x2558
  init_module_from_file+0xe8/0x158
  __arm64_sys_finit_module+0x1f8/0x388
  invoke_syscall.constprop.0+0x64/0xe8
  el0_svc_common.constprop.0+0xc0/0xe8
  do_el0_svc+0x24/0x38
  el0_svc+0x3c/0x198
  el0t_64_sync_handler+0xa0/0xe8
  el0t_64_sync+0x198/0x1a0
 ---[ end trace 0000000000000000 ]---
 inv-mpu6050-i2c 1-0068: Failed to disable vddio regulator: -5

This change introduces variable to track state of vddio regulator and
whether it's needed to disable it or not.

Signed-off-by: Andrey Skvortsov <andrej.skvortzov@gmail.com>
---
 drivers/iio/imu/inv_mpu6050/inv_mpu_core.c | 5 +++++
 drivers/iio/imu/inv_mpu6050/inv_mpu_iio.h  | 1 +
 2 files changed, 6 insertions(+)

diff --git a/drivers/iio/imu/inv_mpu6050/inv_mpu_core.c b/drivers/iio/imu/inv_mpu6050/inv_mpu_core.c
index 5796896d54cd8..7dd09963d5a39 100644
--- a/drivers/iio/imu/inv_mpu6050/inv_mpu_core.c
+++ b/drivers/iio/imu/inv_mpu6050/inv_mpu_core.c
@@ -1843,6 +1843,7 @@ static int inv_mpu_core_enable_regulator_vddio(struct inv_mpu6050_state *st)
 		/* Give the device a little bit of time to start up. */
 		usleep_range(3000, 5000);
 	}
+	st->vddio_supply_en = !result;
 
 	return result;
 }
@@ -1851,10 +1852,14 @@ static int inv_mpu_core_disable_regulator_vddio(struct inv_mpu6050_state *st)
 {
 	int result;
 
+	if (!st->vddio_supply_en)
+		return 0;
+
 	result = regulator_disable(st->vddio_supply);
 	if (result)
 		dev_err(regmap_get_device(st->map),
 			"Failed to disable vddio regulator: %d\n", result);
+	st->vddio_supply_en = false;
 
 	return result;
 }
diff --git a/drivers/iio/imu/inv_mpu6050/inv_mpu_iio.h b/drivers/iio/imu/inv_mpu6050/inv_mpu_iio.h
index 6239b1a803f77..1a2fb857f022d 100644
--- a/drivers/iio/imu/inv_mpu6050/inv_mpu_iio.h
+++ b/drivers/iio/imu/inv_mpu6050/inv_mpu_iio.h
@@ -208,6 +208,7 @@ struct inv_mpu6050_state {
 	struct inv_sensors_timestamp timestamp;
 	struct regulator *vdd_supply;
 	struct regulator *vddio_supply;
+	bool vddio_supply_en;
 	bool magn_disabled;
 	s32 magn_raw_to_gauss[3];
 	struct iio_mount_matrix magn_orient;
-- 
2.51.0