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Date:	Mon, 19 Jan 2015 11:15:41 -0800
From:	Ray Jui <rjui@...adcom.com>
To:	Arend van Spriel <arend@...adcom.com>,
	Uwe Kleine-König 
	<u.kleine-koenig@...gutronix.de>
CC:	Mark Rutland <mark.rutland@....com>, <devicetree@...r.kernel.org>,
	"Ian Campbell" <ijc+devicetree@...lion.org.uk>,
	Florian Fainelli <f.fainelli@...il.com>,
	Russell King <linux@....linux.org.uk>,
	Pawel Moll <pawel.moll@....com>,
	Scott Branden <sbranden@...adcom.com>,
	Wolfram Sang <wsa@...-dreams.de>,
	Christian Daudt <bcm@...thebug.org>,
	<linux-kernel@...r.kernel.org>, Matt Porter <mporter@...aro.org>,
	Rob Herring <robh+dt@...nel.org>,
	<bcm-kernel-feedback-list@...adcom.com>,
	<linux-i2c@...r.kernel.org>, Kumar Gala <galak@...eaurora.org>,
	Grant Likely <grant.likely@...aro.org>,
	<linux-arm-kernel@...ts.infradead.org>
Subject: Re: [PATCH v5 2/3] i2c: iproc: Add Broadcom iProc I2C Driver



On 1/18/2015 4:13 AM, Arend van Spriel wrote:
> On 01/18/15 12:56, Uwe Kleine-König wrote:
>> Hello,
>>
>> On Sun, Jan 18, 2015 at 12:46:51PM +0100, Arend van Spriel wrote:
>>> On 01/18/15 12:17, Uwe Kleine-König wrote:
>>>> Hello Wolfram,
>>>>
>>>> On Sun, Jan 18, 2015 at 12:06:58PM +0100, Wolfram Sang wrote:
>>>>> On Sun, Jan 18, 2015 at 10:47:41AM +0100, Uwe Kleine-König wrote:
>>>>>> On Sun, Jan 18, 2015 at 10:14:04AM +0100, Arend van Spriel wrote:
>>>>>>> On 01/17/15 00:42, Ray Jui wrote:
>>>>>>>> +    complete_all(&iproc_i2c->done);
>>>>>>>
>>>>>>> Looking over this code it seems to me there is always a single
>>>>>>> process waiting for iproc_i2c->done to complete. So using complete()
>>>>>>> here would suffice.
>>>>>> Yeah, there is always only a single thread waiting. That means both
>>>>>> complete and complete_all are suitable. AFAIK there is no reason
>>>>>> to pick
>>>>>> one over the other in this case.
>>>>>
>>>>> Clarity?
>>>> And which do you consider more clear? complete_all might result in the
>>>> question: "Is there>1 waiter?" and complete might yield to "What about
>>>> the other waiters?". If you already know there is only one, both are on
>>>> par on clarity. Might only be me?! I don't care much.
>>>
>>> Maybe it is me, but it is not about questions but it is about
>>> implicit statements that the code makes (or reader derives from it).
>>> When using complete_all you indicate to the reader "there can be
>>> more than one waiter". When using complete it indicates "there is
>>> only one waiter". If those statements are not true that is a code
>> No, complete works just fine in the presence of>1 waiter. It just wakes
>> a single waiter and all others continue to wait.
> 
> Yes. Agree.
> 
>> That is, for single-waiter situations there is no semantic difference
>> between complete and complete_all. But there is a difference for
>> multi-waiter queues.
> 
> Indeed.
> 
>> I think this is just a matter of your POV in the single-waiter
>> situation: complete might be intuitive because you just completed a
>> single task and complete_all might be intuitive because it signals
>> "I'm completely done, there is noone waiting for me any more.".
> 
> Ok. Let's leave it to the author's intuition or to say it differently
> "sorry for the noise" ;-)
Will stay with complete_all since I meant to say "after this transfer
complete interrupt, there should be no one waiting anymore (although
there's currently only one waiter, and will likely stay that way)"

Thanks!

> 
> Regards,
> Arend
> 
>> Best regards
>> Uwe
>>
> 
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