From: Peter Korsgaard <peter@korsgaard.com>
To: Federico Vaga <federico.vaga@cern.ch>
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 14:04:13 +0100 [thread overview]
Message-ID: <87muqwzyya.fsf@dell.be.48ers.dk> (raw)
In-Reply-To: <5352289.A0jT2G1FDH@pcbe13614> (Federico Vaga's message of "Mon, 29 Oct 2018 09:50:15 +0100")
>>>>> "Federico" == Federico Vaga <federico.vaga@cern.ch> writes:
Hi,
>> >> 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.
Ahh yes.
> 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.
Great! BTW I noticed that your sleep_min calculation looked odd:
int sleep_min = (8/i2c->bus_clock_khz) * 1000; /* us for 8bits
bus_clock_khz almost certainly will be bigger than 8 (E.G. likely
100KHz), so the above set sleep_min to 0. Please move the * 1000 before
the division.
--
Bye, Peter Korsgaard
next prev parent reply other threads:[~2018-10-29 13:04 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
2018-10-29 13:04 ` Peter Korsgaard [this message]
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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