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SubjectRe: [PATCH 3/3] i2c:ocores: add polling interface
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Hi Peter,

On Friday, October 26, 2018 7:45:29 PM CET Peter Korsgaard wrote:
> >>>>> "Federico" == Federico Vaga <federico.vaga@cern.ch> writes:
> Hi,
>
> >> > - } else
> >> > + } else {
> >> >
> >> > msg->buf[i2c->pos++] = oc_getreg(i2c, OCI2C_DATA);
> >> >
> >> > + }
> >>
> >> This looks unrelated to $SUBJECT.
> >
> > Do you prefer a different patch just for styling?
>
> Yes please, it is a lot nicer to keep functional changes from pure style
> changes.

Ok

> >> > +static void ocores_poll_wait(struct ocores_i2c *i2c)
> >> > +{
> >> > + int sleep_min = (8/i2c->bus_clock_khz) * 1000; /* us for 8bits
> >> > */
> >> > + u8 loop_on;
> >> > +
> >> > + usleep_range(sleep_min, sleep_min + 10);
> >>
> >> Where does this 10 come from?
> >
> > It's true, it's just a random number. It can be zero as well, and we ask
> > the system to just sleep for that amount of time.
> >
> > (1) usleep_range(sleep_min, sleep_min);
>
> Or just usleep(sleep_min);

This does not exist as far as I know; the alternative is an active wait with
udelay. But then, it is not that different from just start polling TIP or BUSY
flags.

I think that something like this could be better

(2) usleep_range(sleep_min, sleep_min * XXX);

But.
Since it is better to make this patch ready for xfer_irqless, then I will
definitively go for udelay(). The reason is that, xfer_irqless may run in
atomic context where we can't sleep at all.


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