On Thu, Jun 10, 2021 at 4:47 PM Chris Lesiak <chris.lesiak@xxxxxxxxx> wrote:
>
> 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.
This is crucial and not so visible in the code, see below.
> Fixes: 4839367d99e3 ("iio: humidity: add HDC100x support")
> Signed-off-by: Chris Lesiak <chris.lesiak@xxxxxxxxx>
> ---
> drivers/iio/humidity/hdc100x.c | 4 ++--
> 1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/iio/humidity/hdc100x.c b/drivers/iio/humidity/hdc100x.c
> index 2a957f19048e..91790aa8beeb 100644
> --- a/drivers/iio/humidity/hdc100x.c
> +++ b/drivers/iio/humidity/hdc100x.c
> @@ -166,7 +166,7 @@ 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] + 1000;
+ 1 * USEC_PER_MSEC;
> int ret;
> __be16 val;
>
> @@ -316,7 +316,7 @@ 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] + 2000;
+ 2 * USEC_PER_MSEC
> int ret;
>
> /* dual read starts at temp register */
Above might require to add #include <vdso/time64.h>.
--
With Best Regards,
Andy Shevchenko
