[PATCH 5.10 03/96] iio: humidity: hdc100x: Add margin to the conversion time

From: Greg Kroah-Hartman
Date: Mon Aug 16 2021 - 09:11:10 EST

From: Chris Lesiak <chris.lesiak@xxxxxxxxx>

commit 84edec86f449adea9ee0b4912a79ab8d9d65abb7 upstream.

The datasheets have the following note for the conversion time
specification: "This parameter is specified by design and/or
characterization and it is not tested in production."

Parts have been seen that require more time to do 14-bit conversions for
the relative humidity channel. The result is ENXIO due to the address
phase of a transfer not getting an ACK.

Delay an additional 1 ms per conversion to allow for additional margin.

Fixes: 4839367d99e3 ("iio: humidity: add HDC100x support")
Signed-off-by: Chris Lesiak <chris.lesiak@xxxxxxxxx>
Acked-by: Matt Ranostay <matt.ranostay@xxxxxxxxxxxx>
Link: https://lore.kernel.org/r/20210614141820.2034827-1-chris.lesiak@xxxxxxxxx
Cc: <Stable@xxxxxxxxxxxxxxx>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
drivers/iio/humidity/hdc100x.c | 6 ++++--
1 file changed, 4 insertions(+), 2 deletions(-)

--- a/drivers/iio/humidity/hdc100x.c
+++ b/drivers/iio/humidity/hdc100x.c
@@ -25,6 +25,8 @@
#include <linux/iio/trigger_consumer.h>
#include <linux/iio/triggered_buffer.h>

+#include <linux/time.h>
#define HDC100X_REG_TEMP 0x00
#define HDC100X_REG_HUMIDITY 0x01

@@ -166,7 +168,7 @@ static int hdc100x_get_measurement(struc
struct iio_chan_spec const *chan)
struct i2c_client *client = data->client;
- int delay = data->adc_int_us[chan->address];
+ int delay = data->adc_int_us[chan->address] + 1*USEC_PER_MSEC;
int ret;
__be16 val;

@@ -316,7 +318,7 @@ static irqreturn_t hdc100x_trigger_handl
struct iio_dev *indio_dev = pf->indio_dev;
struct hdc100x_data *data = iio_priv(indio_dev);
struct i2c_client *client = data->client;
- int delay = data->adc_int_us[0] + data->adc_int_us[1];
+ int delay = data->adc_int_us[0] + data->adc_int_us[1] + 2*USEC_PER_MSEC;
int ret;

/* dual read starts at temp register */