diff options
| author | Akinobu Mita <akinobu.mita@gmail.com> | 2017-07-20 18:24:20 +0300 |
|---|---|---|
| committer | Jonathan Cameron <Jonathan.Cameron@huawei.com> | 2017-08-20 17:41:13 +0300 |
| commit | 73e3e3fc50de50cfd68e945d85679c983ed31bd9 (patch) | |
| tree | e6277bcfcd388098fb38483ba4df45cfff750226 /drivers/iio | |
| parent | e8245c68350104b6022b6783719e843d69ea7c43 (diff) | |
| download | linux-73e3e3fc50de50cfd68e945d85679c983ed31bd9.tar.xz | |
iio: adc: ti-ads1015: avoid getting stale result after runtime resume
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>
Cc: <Stable@vger.kernel.org>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Diffstat (limited to 'drivers/iio')
| -rw-r--r-- | drivers/iio/adc/ti-ads1015.c | 18 |
1 files changed, 16 insertions, 2 deletions
diff --git a/drivers/iio/adc/ti-ads1015.c b/drivers/iio/adc/ti-ads1015.c index 9d77e837c09b..2f52b149f49a 100644 --- a/drivers/iio/adc/ti-ads1015.c +++ b/drivers/iio/adc/ti-ads1015.c @@ -177,6 +177,12 @@ 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) @@ -255,9 +261,10 @@ 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); @@ -630,6 +637,8 @@ 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; @@ -685,10 +694,15 @@ 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 |