Hi Jonathan,
see answer to your question below.
Andreas
Jonathan Cameron <jic23@xxxxxxxxxx> schrieb am Sat, 02. Dec 13:22:
> On Thu, 30 Nov 2017 22:44:45 +0100
> Andreas Klinger <ak@xxxxxxxxxxxxx> wrote:
>
> > return value in hx711_reset() should indicate status of dout
> > otherwise the calling function is reporting an error als false positive
> >
> > wait up to 1 second until the device is in normal state
> > by changing the channel on every trigger event it turned out that the
> > former 100 ms are not enough for waiting until the device is in normal mode
>
> What is the ultimate result of this? I'm trying to assess if we want
> to marked it for stable trees or just apply it ready for the next
> merge window. It think it means that two reads too close to each
> other will always result in an error for the second one rather than
> the intended delay and then succeed?
Exactly. If one is accessing to fast the second access will fail. Especially
when using a trigger the second channel is never read without error.
>
> Thanks,
>
> Jonathan
> >
> > Signed-off-by: Andreas Klinger <ak@xxxxxxxxxxxxx>
> > ---
> > drivers/iio/adc/hx711.c | 13 ++++++-------
> > 1 file changed, 6 insertions(+), 7 deletions(-)
> >
> > diff --git a/drivers/iio/adc/hx711.c b/drivers/iio/adc/hx711.c
> > index d773fd69a76d..eabd2e66aca3 100644
> > --- a/drivers/iio/adc/hx711.c
> > +++ b/drivers/iio/adc/hx711.c
> > @@ -153,15 +153,16 @@ static int hx711_wait_for_ready(struct hx711_data *hx711_data)
> > int i, val;
> >
> > /*
> > - * a maximum reset cycle time of 56 ms was measured.
> > - * we round it up to 100 ms
> > + * in some rare cases the reset takes quite a long time
> > + * especially when the channel is changed.
> > + * Allow up to one second for it
> > */
> > for (i = 0; i < 100; i++) {
> > val = gpiod_get_value(hx711_data->gpiod_dout);
> > if (!val)
> > break;
> > - /* sleep at least 1 ms */
> > - msleep(1);
> > + /* sleep at least 10 ms */
> > + msleep(10);
> > }
> > if (val)
> > return -EIO;
> > @@ -203,9 +204,7 @@ static int hx711_reset(struct hx711_data *hx711_data)
> > * after a dummy read we need to wait vor readiness
> > * for not mixing gain pulses with the clock
> > */
> > - ret = hx711_wait_for_ready(hx711_data);
> > - if (ret)
> > - return ret;
> > + val = hx711_wait_for_ready(hx711_data);
> > }
> >
> > return val;
>
--
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