From a130404ce0b69ca1438126bd81c1985d3b4d2e6f Mon Sep 17 00:00:00 2001 From: Erick Henrique Date: Fri, 3 Jul 2026 17:52:36 -0300 Subject: [PATCH] iio: dac: m62332: Fix regulator reference count imbalance m62332_set_value() enables the Vcc regulator on every write of a non-zero value and disables it on every write of zero, without tracking the channel's current state. Because the regulator is reference counted, changing a channel directly from one non-zero value to another enables it more than once, while a later write of zero disables it only once. The reference count never returns to zero and the regulator is left enabled indefinitely. Only enable the regulator on the transition from zero to non-zero, and only disable it on the transition from non-zero to zero, using the previously stored channel value to detect the edge. Balance the regulator on the I2C error path so the reference count stays consistent if the write fails. Fixes: b87b0c0f81e8 ("iio: add m62332 DAC driver") Reported-by: Sashiko Closes: https://sashiko.dev/#/patchset/20260418130322.106769-1-erick.henrique.rodrigues%40usp.br Cc: stable@vger.kernel.org Signed-off-by: Erick Henrique Signed-off-by: Jonathan Cameron --- drivers/iio/dac/m62332.c | 17 ++++++++++++----- 1 file changed, 12 insertions(+), 5 deletions(-) diff --git a/drivers/iio/dac/m62332.c b/drivers/iio/dac/m62332.c index 7e80c0eb5cc1..60bb672b70e2 100644 --- a/drivers/iio/dac/m62332.c +++ b/drivers/iio/dac/m62332.c @@ -32,6 +32,7 @@ static int m62332_set_value(struct iio_dev *indio_dev, u8 val, int channel) { struct m62332_data *data = iio_priv(indio_dev); struct i2c_client *client = data->client; + bool enabling, disabling; u8 outbuf[2]; int res; @@ -43,7 +44,10 @@ static int m62332_set_value(struct iio_dev *indio_dev, u8 val, int channel) mutex_lock(&data->mutex); - if (val) { + enabling = val && !data->raw[channel]; + disabling = !val && data->raw[channel]; + + if (enabling) { res = regulator_enable(data->vcc); if (res) goto out; @@ -52,14 +56,17 @@ static int m62332_set_value(struct iio_dev *indio_dev, u8 val, int channel) res = i2c_master_send(client, outbuf, ARRAY_SIZE(outbuf)); if (res >= 0 && res != ARRAY_SIZE(outbuf)) res = -EIO; - if (res < 0) + if (res < 0) { + if (enabling) + regulator_disable(data->vcc); goto out; + } + + if (disabling) + regulator_disable(data->vcc); data->raw[channel] = val; - if (!val) - regulator_disable(data->vcc); - mutex_unlock(&data->mutex); return 0;