iio: humidity: hdc100x: Add margin to the conversion time

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@licor.com>
Acked-by: Matt Ranostay <matt.ranostay@konsulko.com>
Link: https://lore.kernel.org/r/20210614141820.2034827-1-chris.lesiak@licor.com
Cc: <Stable@vger.kernel.org>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/iio/humidity/hdc100x.c b/drivers/iio/humidity/hdc100x.c
index 0fcaa2c0b2f4387bf53a29d7d0c0bcf9f1b57dd0..51ad5a9ed085156518931d17a0ce401fad78212d 100644 (file)
--- a/drivers/iio/humidity/hdc100x.c
+++ b/drivers/iio/humidity/hdc100x.c
@@ -24,6 +24,8 @@
 #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
 
@@ -165,7 +167,7 @@ static int hdc100x_get_measurement(struct hdc100x_data *data,
                                   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;
 
@@ -322,7 +324,7 @@ static irqreturn_t hdc100x_trigger_handler(int irq, void *p)
        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 */