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: Fri, 26 Oct 2018 19:45:29 +0200 [thread overview]
Message-ID: <87woq438li.fsf@dell.be.48ers.dk> (raw)
In-Reply-To: <4222986.LvGMQbjSbS@pcbe13614> (Federico Vaga's message of "Wed, 24 Oct 2018 11:51:19 +0200")
>>>>> "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.
>> > +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);
>>
>> > + if (i2c->state == STATE_DONE || i2c->state == STATE_ERROR)
>> > + loop_on = OCI2C_STAT_BUSY;
>> > + else
>> > + loop_on = OCI2C_STAT_TIP;
>> > + while (oc_getreg(i2c, OCI2C_STATUS) & loop_on)
>> > + ;
>>
>> How would an I2C transmission timeout be handled here?
> There is the assumption that the hardware is alive and what we read from
> oc_getreg() is correct. With this assumption, when there is a timeout this
> will happen:
> 1. STOP command (previous patch)
> 2. both TIP and BUSY will become zero at some point and we get out from the
> loop
> I can see now that there are cases when it may loop forever: for example if
> the device is broken and it does answer always with 0xFFFF: we should not
> break the host as well :)
> I can fix this.
Thanks!
--
Bye, Peter Korsgaard
next prev parent reply other threads:[~2018-10-26 17:45 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 [this message]
2018-10-29 8:50 ` Federico Vaga
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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