@@ -5492,7 +5492,38 @@ regulator_register(const struct regulator_desc =
*regulator_desc,
BLOCKING_INIT_NOTIFIER_HEAD(&rdev->notifier);
INIT_DELAYED_WORK(&rdev->disable_work, regulator_disable_work);
=20
- /* preform any regulator specific init */
+ /* set regulator constraints */
+ if (init_data)
+ rdev->constraints =3D kmemdup(&init_data->constraints,
+ sizeof(*rdev->constraints),
+ GFP_KERNEL);
+ else
+ rdev->constraints =3D =
kzalloc(sizeof(*rdev->constraints),
+ GFP_KERNEL);
+ if (!rdev->constraints) {
+ ret =3D -ENOMEM;
+ goto clean;
+ }
+
+ if (init_data && init_data->supply_regulator)
+ rdev->supply_name =3D init_data->supply_regulator;
+ else if (regulator_desc->supply_name)
+ rdev->supply_name =3D regulator_desc->supply_name;
+
+ if ((rdev->supply_name && !rdev->supply) && rdev->constraints
+ && (rdev->constraints->always_on || =
rdev->constraints->boot_on)) {
+ /* Try to resolve the name of the supplying regulator =
here first
+ * so we prevent double-initializing the regulator, =
which may
+ * cause timing-specific voltage brownouts/glitches that =
are
+ * hard to debug.
+ */
+ ret =3D regulator_resolve_supply(rdev);
+ if (ret)
+ rdev_dbg(rdev, "unable to resolve supply early: =
%pe\n",
Previously, an unresolved regulator supply reference upon calling regulator_register on an always-on or boot-on regulator caused set_machine_constraints to be called twice. This in turn may initialize the regulator twice, leading to voltage glitches that are timing-dependent. A simple, unrelated configuration change may be enough to hide this problem, only to be surfaced by chance. One such example is the SD-Card voltage regulator in a NanoPI R4S that would not initialize reliably unless the registration flow was just complex enough to allow the regulator to properly reset between calls. Fix this by re-arranging regulator_register, trying resolve the regulator's supply early enough that set_machine_constraints does not need to be called twice. Signed-off-by: Christian Kohlsch=C3=BCtter <christian@kohlschutter.com> --- drivers/regulator/core.c | 51 +++++++++++++++++++++++++--------------- 1 file changed, 32 insertions(+), 19 deletions(-) + ERR_PTR(ret)); + } + + /* perform any regulator specific init */ if (init_data && init_data->regulator_init) { ret =3D init_data->regulator_init(rdev->reg_data); if (ret < 0) @@ -5518,24 +5549,6 @@ regulator_register(const struct regulator_desc = *regulator_desc, (unsigned long) atomic_inc_return(®ulator_no)); dev_set_drvdata(&rdev->dev, rdev); =20 - /* set regulator constraints */ - if (init_data) - rdev->constraints =3D kmemdup(&init_data->constraints, - sizeof(*rdev->constraints), - GFP_KERNEL); - else - rdev->constraints =3D = kzalloc(sizeof(*rdev->constraints), - GFP_KERNEL); - if (!rdev->constraints) { - ret =3D -ENOMEM; - goto wash; - } - - if (init_data && init_data->supply_regulator) - rdev->supply_name =3D init_data->supply_regulator; - else if (regulator_desc->supply_name) - rdev->supply_name =3D regulator_desc->supply_name; - ret =3D set_machine_constraints(rdev); if (ret =3D=3D -EPROBE_DEFER) { /* Regulator might be in bypass mode and so needs its = supply --=20 2.36.2