Re: [PATCH v5 2/3] i2c: iproc: Add Broadcom iProc I2C Driver

Ray Jui
2015-01-19T19:15:49Z

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
>>
>