2017-08-25 14:39 GMT+09:00 Ladislav Michl <ladis@xxxxxxxxxxxxxx>: > As user's guide "ADS1015EVM, ADS1115EVM, ADS1015EVM-PDK, ADS1115EVM-PDK > User Guide (Rev. B)" (http://www.ti.com/lit/ug/sbau157b/sbau157b.pdf) > states at page 16: > "Note that both the ADS1115 and ADS1015 have internal clocks with a ±10% > accuracy. If performing FFT tests, frequencies may appear to be incorrect > as a result of this tolerance range.", add those 10% to converion wait > time. > > Cc: Daniel Baluta <daniel.baluta@xxxxxxxxx> > Cc: Jonathan Cameron <jic23@xxxxxxxxxx> > Cc: Akinobu Mita <akinobu.mita@xxxxxxxxx> > Signed-off-by: Ladislav Michl <ladis@xxxxxxxxxxxxxx> > --- > Changes: > -v2: Add comment explaining why those 10% are needed > > drivers/iio/adc/ti-ads1015.c | 1 + > 1 file changed, 1 insertion(+) > > diff --git a/drivers/iio/adc/ti-ads1015.c b/drivers/iio/adc/ti-ads1015.c > index 034e48566ab5..ae29dd87c597 100644 > --- a/drivers/iio/adc/ti-ads1015.c > +++ b/drivers/iio/adc/ti-ads1015.c > @@ -268,6 +268,7 @@ int ads1015_get_adc_result(struct ads1015_data *data, int chan, int *val) > dr_old = (old & ADS1015_CFG_DR_MASK) >> ADS1015_CFG_DR_SHIFT; > conv_time = DIV_ROUND_UP(USEC_PER_SEC, data->data_rate[dr_old]); > conv_time += DIV_ROUND_UP(USEC_PER_SEC, data->data_rate[dr]); > + conv_time += conv_time / 10; /* 10% internal clock inaccuracy */ Perhaps we'd better use DIV_ROUND_UP to avoid the worst case. Anyway, this and patch 2/2 look good to me. Reviewed-by: Akinobu Mita <akinobu.mita@xxxxxxxxx> > usleep_range(conv_time, conv_time + 1); > data->conv_invalid = false; > } > -- > 2.11.0 > -- To unsubscribe from this list: send the line "unsubscribe linux-iio" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
