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authorAkinobu Mita <akinobu.mita@gmail.com>2017-07-20 17:24:20 +0200
committerJonathan Cameron <Jonathan.Cameron@huawei.com>2017-08-20 16:41:13 +0200
commit73e3e3fc50de50cfd68e945d85679c983ed31bd9 (patch)
treee6277bcfcd388098fb38483ba4df45cfff750226 /drivers/iio
parentiio: adc: ti-ads1015: enable conversion when CONFIG_PM is not set (diff)
downloadlinux-73e3e3fc50de50cfd68e945d85679c983ed31bd9.tar.xz
linux-73e3e3fc50de50cfd68e945d85679c983ed31bd9.zip
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.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 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