From: Federico Vaga <federico.vaga@cern.ch>
To: Peter Korsgaard <peter@korsgaard.com>
Cc: Peter Korsgaard <jacmet@sunsite.dk>,
linux-i2c <linux-i2c@vger.kernel.org>,
<linux-kernel@vger.kernel.org>
Subject: Re: [PATCH 3/3] i2c:ocores: add polling interface
Date: Mon, 29 Oct 2018 09:50:15 +0100 [thread overview]
Message-ID: <5352289.A0jT2G1FDH@pcbe13614> (raw)
In-Reply-To: <87woq438li.fsf@dell.be.48ers.dk>
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.
next prev parent reply other threads:[~2018-10-29 8:50 UTC|newest]
Thread overview: 24+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-06-25 16:13 i2c:ocores: fixes and polling mechanism Federico Vaga
2018-06-25 16:13 ` [PATCH 1/3] i2c:ocores: stop transfer on timeout Federico Vaga
2018-10-21 14:10 ` Peter Korsgaard
2018-10-24 14:51 ` Federico Vaga
2018-10-26 17:46 ` Peter Korsgaard
2018-10-25 7:42 ` Federico Vaga
2018-06-25 16:13 ` [PATCH 2/3] i2c:ocores: do not handle IRQ if IF is not set Federico Vaga
2018-10-21 14:12 ` Peter Korsgaard
2018-10-29 8:53 ` Wolfram Sang
2018-10-29 14:27 ` Federico Vaga
2018-06-25 16:13 ` [PATCH 3/3] i2c:ocores: add polling interface Federico Vaga
2018-10-21 14:39 ` Peter Korsgaard
2018-10-24 9:51 ` Federico Vaga
2018-10-26 17:45 ` Peter Korsgaard
2018-10-29 8:50 ` Federico Vaga [this message]
2018-10-29 13:04 ` Peter Korsgaard
2018-10-29 13:11 ` Federico Vaga
2018-10-25 7:47 ` Federico Vaga
2018-08-11 17:13 ` i2c:ocores: fixes and polling mechanism Federico Vaga
2018-08-12 15:34 ` Wolfram Sang
2018-08-22 16:16 ` Peter Korsgaard
2018-09-17 16:42 ` Wolfram Sang
2018-09-19 5:15 ` Peter Korsgaard
2018-09-19 6:51 ` Wolfram Sang
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