On Thu, 30 Sep 2021 17:18:44 +0100
Jonathan Cameron <jic23@xxxxxxxxxx> wrote:
> On Sun, 26 Sep 2021 23:18:42 +0200
> Thomas Gleixner <tglx@xxxxxxxxxxxxx> wrote:
>
> > On Sun, Sep 26 2021 at 18:16, Iain Hunter wrote:
> > > --- a/drivers/iio/adc/ina2xx-adc.c
> > > +++ b/drivers/iio/adc/ina2xx-adc.c
> > > @@ -817,10 +817,10 @@ static int ina2xx_capture_thread(void *data)
> > > */
> > > do {
> > > timespec64_add_ns(&next, 1000 * sampling_us);
> > > - delta = timespec64_sub(next, now);
> > > - delay_us = div_s64(timespec64_to_ns(&delta), 1000);
> > > - } while (delay_us <= 0);
> > > + } while (timespec64_compare(&next, &now) < 0);
> > >
> > > + delta = timespec64_sub(next, now);
> > > + delay_us = div_s64(timespec64_to_ns(&delta), 1000);
> >
> > This whole timespec dance does not make any sense and can be completely
> > avoided by using just scalar nanoseconds. Untested patch below.
> >
> > Thanks,
> >
> > tglx
>
> Thanks Thomas.
>
> Iain could you test this approach?
Ah. Just seen v4, so I guess you did.
Thanks,
J
>
> Thanks,
>
> Jonathan
>
> > ---
> > --- a/drivers/iio/adc/ina2xx-adc.c
> > +++ b/drivers/iio/adc/ina2xx-adc.c
> > @@ -775,7 +775,7 @@ static int ina2xx_capture_thread(void *d
> > struct ina2xx_chip_info *chip = iio_priv(indio_dev);
> > int sampling_us = SAMPLING_PERIOD(chip);
> > int ret;
> > - struct timespec64 next, now, delta;
> > + ktime_t next, now, delta;
> > s64 delay_us;
> >
> > /*
> > @@ -785,7 +785,7 @@ static int ina2xx_capture_thread(void *d
> > if (!chip->allow_async_readout)
> > sampling_us -= 200;
> >
> > - ktime_get_ts64(&next);
> > + next = ktime_get();
> >
> > do {
> > while (!chip->allow_async_readout) {
> > @@ -798,7 +798,7 @@ static int ina2xx_capture_thread(void *d
> > * reset the reference timestamp.
> > */
> > if (ret == 0)
> > - ktime_get_ts64(&next);
> > + next = ktime_get();
> > else
> > break;
> > }
> > @@ -807,7 +807,7 @@ static int ina2xx_capture_thread(void *d
> > if (ret < 0)
> > return ret;
> >
> > - ktime_get_ts64(&now);
> > + now = ktime_get();
> >
> > /*
> > * Advance the timestamp for the next poll by one sampling
> > @@ -816,11 +816,10 @@ static int ina2xx_capture_thread(void *d
> > * multiple times, i.e. samples are dropped.
> > */
> > do {
> > - timespec64_add_ns(&next, 1000 * sampling_us);
> > - delta = timespec64_sub(next, now);
> > - delay_us = div_s64(timespec64_to_ns(&delta), 1000);
> > - } while (delay_us <= 0);
> > + next = ktime_add_us(next, sampling_us);
> > + } while (next <= now);
> >
> > + delay_us = ktime_to_us(ktime_sub(next, now));
> > usleep_range(delay_us, (delay_us * 3) >> 1);
> >
> > } while (!kthread_should_stop());
> >
> >
>
