Re: [PATCH 1/2] iio: adc: ti-ads1015: fix conversion time

[Ladislav Michl <ladis@linux-mips.org>]

On Tue, Aug 01, 2017 at 12:09:34PM +0300, Daniel Baluta wrote:
> On Tue, Aug 1, 2017 at 11:26 AM, Ladislav Michl <ladis@linux-mips.org> wrote:
> > When reading diffrent channel value than device is currently processing
> > wait time of conversion period is applied, which is not enough as device
> > might be already in the middle of conversion and therefore previously
> > converted value is returned - the one belonging to another channel.
> > Fix it by waiting for two sampling periods.
> >
> > Signed-off-by: Ladislav Michl <ladis@linux-mips.org>
> 
> Did you actually experienced this in practice? I guess you are right,
> if you change the channel during a conversion, this change will be applied
> to the next conversion *but* reading will still return old value because the
> current conversion hasn't finished yet.

Yes, that's what actually happens without patch and could be easily
demonstrated from command line:

$ cat in_voltage0_raw
847
$ cat in_voltage1_raw
846
$ cat in_voltage1_raw
195
$ cat in_voltage0_raw
196
$ cat in_voltage0_raw
846

Btw, driver is using continuous conversion mode, but I was unable to
make iio_generic_buffer work with it. And for reading values one by
one single shot mode is enough. Any hints?

Thank you,
	ladis

> So,
> 
> Acked-by: Daniel Baluta <daniel.baluta@gmail.com>