Jonathan Cameron <ji...@kernel.org> 於 2018年11月25日 週日 下午9:23寫道： > > On Wed, 21 Nov 2018 13:13:40 +0800 > Jian-Hong Pan <jian-h...@endlessm.com> wrote: > > > Denis CIOCCA <denis.cio...@st.com> 於 2018年11月20日 週二 上午3:05寫道： > > > > > > Hi Jian, > > > > > > Not clear to me why should be + instead of *. > > > > > > ODR is expressed in Hz, so (1/Hz) = period in seconds (1 sample sampling > > > time) [s] > > > 1000 * (1/Hz) = period in milliseconds (1 sample sampling time) [ms] > > > n * 1000 * (1/Hz) = n times period in milliseconds (n times sample > > > sampling time) [ms] > > > > > > In your case you assume bootime is in milliseconds. > > > > Yes, I assume that according to the original comment. > > > > >Maybe we can change the comment and use 'number of samples ...'. > > > > Making the meaning more clear is better. > > > > However, does the bootime of the measurement need as the long time to > > be enabled? > > If the sampling rate is 1Hz and n is 2, then they will do msleep with > > 2000 ms for each st_sensors_read_info_raw. > > Superficially that seems correct as we need to be sure that a reading > has occurred. If you want it to be quicker than the ODR should be set > faster so that the reading shows up reasonably quickly. At 1Hz and > you want to drop 2 samples, it will indeed take 2 seconds.
Now, I understand with the description. Thank you. Jian-Hong Pan > > > -----Original Message----- > > > From: linux-iio-ow...@vger.kernel.org <linux-iio-ow...@vger.kernel.org> > > > On Behalf Of Jian-Hong Pan > > > Sent: Sunday, November 18, 2018 10:12 PM > > > To: Jonathan Cameron <ji...@kernel.org>; Hartmut Knaack > > > <knaac...@gmx.de>; Lars-Peter Clausen <l...@metafoo.de>; Peter > > > Meerwald-Stadler <pme...@pmeerw.net>; Dominique Martinet > > > <asmad...@codewreck.org> > > > Cc: linux-...@vger.kernel.org; linux-kernel@vger.kernel.org; > > > li...@endlessm.com; Jian-Hong Pan <jian-h...@endlessm.com> > > > Subject: [PATCH] iio: st_sensors: Fix the sleep time for sampling > > > > > > According to the description of st_sensor_settings and st_sensor_data > > > structures' comments: > > > - bootime: samples to discard when sensor passing from power-down to > > > power-up. > > > - odr: Output data rate of the sensor [Hz]. > > > > > > The sleep time should be > > > sdata->sensor_settings->bootime + 1000 / sdata->odr ms. > > > > > > Signed-off-by: Jian-Hong Pan <jian-h...@endlessm.com> > > > --- > > > drivers/iio/common/st_sensors/st_sensors_core.c | 2 +- > > > 1 file changed, 1 insertion(+), 1 deletion(-) > > > > > > diff --git a/drivers/iio/common/st_sensors/st_sensors_core.c > > > b/drivers/iio/common/st_sensors/st_sensors_core.c > > > index 26fbd1bd9413..6b87ea657a92 100644 > > > --- a/drivers/iio/common/st_sensors/st_sensors_core.c > > > +++ b/drivers/iio/common/st_sensors/st_sensors_core.c > > > @@ -594,7 +594,7 @@ int st_sensors_read_info_raw(struct iio_dev > > > *indio_dev, > > > if (err < 0) > > > goto out; > > > > > > - msleep((sdata->sensor_settings->bootime * 1000) / > > > sdata->odr); > > > + msleep(sdata->sensor_settings->bootime + 1000 / > > > sdata->odr); > > > err = st_sensors_read_axis_data(indio_dev, ch, val); > > > if (err < 0) > > > goto out; > > > -- > > > 2.11.0 > > > >
