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hwmon: (ads7828) Fix external VREF regulator handling

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The driver currently has two issues with the external VREF regulator
handling in ads7828_probe():

1. All errors from devm_regulator_get_optional() are ignored, causing the
   driver to incorrectly fall back to internal VREF even for transient
   errors like -EPROBE_DEFER or genuine failures like -ENOMEM.

2. The external regulator is never enabled. The driver calls
   regulator_get_voltage() without first calling regulator_enable(),
   so the VREF pin may remain unpowered if the regulator is not
   configured as always-on.

Fix both issues by switching to devm_regulator_get_enable_read_voltage(),
which handles regulator get, enable, and voltage read in one call.
Only -ENODEV (no regulator specified in device tree) should trigger the
fallback to internal VREF. All other errors are propagated to the caller.

Fixes: a8ddfea095 ("hwmon: (ads7828) Accept optional parameters from device tree")
Signed-off-by: Qingshuang Fu <fuqingshuang@kylinos.cn>
Link: https://lore.kernel.org/r/20260805061645.1331652-1-fffsqian@163.com
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
This commit is contained in:
Qingshuang Fu
2026-08-05 14:16:45 +08:00
committed by Guenter Roeck
parent 36c4d73ce0
commit fddb5ceaf9
1 changed files with 6 additions and 5 deletions
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11
drivers/hwmon/ads7828.c
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@@ -106,12 +106,11 @@ static int ads7828_probe(struct i2c_client *client)
struct ads7828_data *data;
struct device *hwmon_dev;
unsigned int vref_mv = ADS7828_INT_VREF_MV;
unsigned int vref_uv;
int vref_uv;
bool diff_input = false;
bool ext_vref = false;
unsigned int regval;
enum ads7828_chips chip;
struct regulator *reg;
data = devm_kzalloc(dev, sizeof(struct ads7828_data), GFP_KERNEL);
if (!data)
@@ -125,9 +124,11 @@ static int ads7828_probe(struct i2c_client *client)
} else if (dev->of_node) {
diff_input = of_property_read_bool(dev->of_node,
"ti,differential-input");
reg = devm_regulator_get_optional(dev, "vref");
if (!IS_ERR(reg)) {
vref_uv = regulator_get_voltage(reg);
vref_uv = devm_regulator_get_enable_read_voltage(dev, "vref");
if (vref_uv < 0) {
if (vref_uv != -ENODEV)
return vref_uv;
} else {
vref_mv = DIV_ROUND_CLOSEST(vref_uv, 1000);
if (vref_mv < ADS7828_EXT_VREF_MV_MIN ||
vref_mv > ADS7828_EXT_VREF_MV_MAX)