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authorChristian Kohlschütter <christian@kohlschutter.com>2022-08-18 15:46:47 +0300
committerMark Brown <broonie@kernel.org>2022-08-18 17:02:07 +0300
commit8a866d527ac0441c0eb14a991fa11358b476b11d (patch)
tree111b2fe8e387d492e27a1db1d3d857826e9ff5e2 /drivers/regulator
parentee94aff2628b18afdb0b6b175e568657bdaead59 (diff)
downloadlinux-8a866d527ac0441c0eb14a991fa11358b476b11d.tar.xz
regulator: core: Resolve supply name earlier to prevent double-init
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 Kohlschütter <christian@kohlschutter.com> Link: https://lore.kernel.org/r/20220818124646.6005-1-christian@kohlschutter.com Signed-off-by: Mark Brown <broonie@kernel.org>
Diffstat (limited to 'drivers/regulator')
-rw-r--r--drivers/regulator/core.c52
1 files changed, 33 insertions, 19 deletions
diff --git a/drivers/regulator/core.c b/drivers/regulator/core.c
index d8373cb04f90..a5033c6ba01e 100644
--- a/drivers/regulator/core.c
+++ b/drivers/regulator/core.c
@@ -5496,7 +5496,39 @@ regulator_register(const struct regulator_desc *regulator_desc,
BLOCKING_INIT_NOTIFIER_HEAD(&rdev->notifier);
INIT_DELAYED_WORK(&rdev->disable_work, regulator_disable_work);
- /* preform any regulator specific init */
+ /* set regulator constraints */
+ if (init_data)
+ rdev->constraints = kmemdup(&init_data->constraints,
+ sizeof(*rdev->constraints),
+ GFP_KERNEL);
+ else
+ rdev->constraints = kzalloc(sizeof(*rdev->constraints),
+ GFP_KERNEL);
+ if (!rdev->constraints) {
+ ret = -ENOMEM;
+ goto clean;
+ }
+
+ if (init_data && init_data->supply_regulator)
+ rdev->supply_name = init_data->supply_regulator;
+ else if (regulator_desc->supply_name)
+ rdev->supply_name = regulator_desc->supply_name;
+
+ if ((rdev->supply_name && !rdev->supply) &&
+ (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 = regulator_resolve_supply(rdev);
+ if (ret)
+ rdev_dbg(rdev, "unable to resolve supply early: %pe\n",
+ ERR_PTR(ret));
+ }
+
+ /* perform any regulator specific init */
if (init_data && init_data->regulator_init) {
ret = init_data->regulator_init(rdev->reg_data);
if (ret < 0)
@@ -5522,24 +5554,6 @@ regulator_register(const struct regulator_desc *regulator_desc,
(unsigned long) atomic_inc_return(&regulator_no));
dev_set_drvdata(&rdev->dev, rdev);
- /* set regulator constraints */
- if (init_data)
- rdev->constraints = kmemdup(&init_data->constraints,
- sizeof(*rdev->constraints),
- GFP_KERNEL);
- else
- rdev->constraints = kzalloc(sizeof(*rdev->constraints),
- GFP_KERNEL);
- if (!rdev->constraints) {
- ret = -ENOMEM;
- goto wash;
- }
-
- if (init_data && init_data->supply_regulator)
- rdev->supply_name = init_data->supply_regulator;
- else if (regulator_desc->supply_name)
- rdev->supply_name = regulator_desc->supply_name;
-
ret = set_machine_constraints(rdev);
if (ret == -EPROBE_DEFER) {
/* Regulator might be in bypass mode and so needs its supply