This is a note to let you know that I've just added the patch titled
iio: adc: ti-ads1015: avoid getting stale result after runtime resume
to my staging git tree which can be found at
git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/staging.git
in the staging-next branch.
The patch will show up in the next release of the linux-next tree
(usually sometime within the next 24 hours during the week.)
The patch will also be merged in the next major kernel release
during the merge window.
If you have any questions about this process, please let me know.
>From 73e3e3fc50de50cfd68e945d85679c983ed31bd9 Mon Sep 17 00:00:00 2001
From: Akinobu Mita <akinobu.mita@xxxxxxxxx>
Date: Fri, 21 Jul 2017 00:24:20 +0900
Subject: 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@xxxxxxxxx>
Signed-off-by: Akinobu Mita <akinobu.mita@xxxxxxxxx>
Cc: <Stable@xxxxxxxxxxxxxxx>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@xxxxxxxxxx>
---
drivers/iio/adc/ti-ads1015.c | 18 ++++++++++++++++--
1 file 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
--
2.14.1