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authorAkinobu Mita <akinobu.mita@gmail.com>2017-07-21 00:24:20 +0900
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2017-09-09 17:39:38 +0200
commit1ed4565b7c7bb73d802800c333244498f0993274 (patch)
tree491d3532cb709437141ec027798d2355721fb461
parentc72ad1a4fdf044c5253a72bc413e1869d6b16f39 (diff)
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iio: adc: ti-ads1015: avoid getting stale result after runtime resume
commit 73e3e3fc50de50cfd68e945d85679c983ed31bd9 upstream. This driver assumes that the device is operating in the continuous conversion mode which performs the conversion continuously. So this driver doesn't insert a wait time before reading the conversion register if the configuration is not changed from a previous request. This assumption is broken if the device is runtime suspended and entered a power-down state. The forthcoming request causes reading a stale result from the conversion register as the device is runtime resumed just before. Fix it by adding a flag to detect that condition and insert a necessary wait time. Cc: Daniel Baluta <daniel.baluta@gmail.com> Signed-off-by: Akinobu Mita <akinobu.mita@gmail.com> Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
-rw-r--r--drivers/iio/adc/ti-ads1015.c18
1 files changed, 16 insertions, 2 deletions
diff --git a/drivers/iio/adc/ti-ads1015.c b/drivers/iio/adc/ti-ads1015.c
index c6eeb0cf7868..abd3a10f4b1c 100644
--- a/drivers/iio/adc/ti-ads1015.c
+++ b/drivers/iio/adc/ti-ads1015.c
@@ -176,6 +176,12 @@ struct ads1015_data {
struct ads1015_channel_data channel_data[ADS1015_CHANNELS];
unsigned int *data_rate;
+ /*
+ * Set to true when the ADC is switched to the continuous-conversion
+ * mode and exits from a power-down state. This flag is used to avoid
+ * getting the stale result from the conversion register.
+ */
+ bool conv_invalid;
};
static bool ads1015_is_writeable_reg(struct device *dev, unsigned int reg)
@@ -254,9 +260,10 @@ int ads1015_get_adc_result(struct ads1015_data *data, int chan, int *val)
if (ret < 0)
return ret;
- if (change) {
+ if (change || data->conv_invalid) {
conv_time = DIV_ROUND_UP(USEC_PER_SEC, data->data_rate[dr]);
usleep_range(conv_time, conv_time + 1);
+ data->conv_invalid = false;
}
return regmap_read(data->regmap, ADS1015_CONV_REG, val);
@@ -624,6 +631,8 @@ static int ads1015_probe(struct i2c_client *client,
if (ret)
return ret;
+ data->conv_invalid = true;
+
ret = pm_runtime_set_active(&client->dev);
if (ret)
goto err_buffer_cleanup;
@@ -679,10 +688,15 @@ static int ads1015_runtime_resume(struct device *dev)
{
struct iio_dev *indio_dev = i2c_get_clientdata(to_i2c_client(dev));
struct ads1015_data *data = iio_priv(indio_dev);
+ int ret;
- return regmap_update_bits(data->regmap, ADS1015_CFG_REG,
+ ret = regmap_update_bits(data->regmap, ADS1015_CFG_REG,
ADS1015_CFG_MOD_MASK,
ADS1015_CONTINUOUS << ADS1015_CFG_MOD_SHIFT);
+ if (!ret)
+ data->conv_invalid = true;
+
+ return ret;
}
#endif