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. Maybe we can change the 
comment and use 'number of samples ...'.

Br,
Denis



-----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

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