linux-kernel - Re: [PATCH v10 5/6] rtc: max77686: Use ffs() to calculate tm

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Message-ID: <541CA3BA.6060905@collabora.co.uk>
Date:	Fri, 19 Sep 2014 23:44:26 +0200
From:	Javier Martinez Canillas <javier.martinez@...labora.co.uk>
To:	Joe Perches <joe@...ches.com>
CC:	Andrew Morton <akpm@...ux-foundation.org>,
	Alessandro Zummo <a.zummo@...ertech.it>,
	Doug Anderson <dianders@...omium.org>,
	Krzysztof Kozlowski <k.kozlowski@...sung.com>,
	rtc-linux@...glegroups.com, linux-samsung-soc@...r.kernel.org,
	linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v10 5/6] rtc: max77686: Use ffs() to calculate tm_wday

Hello Joe,

On 09/19/2014 09:52 PM, Joe Perches wrote:
> On Fri, 2014-09-19 at 21:27 +0200, Javier Martinez Canillas wrote:
>> On 09/19/2014 04:39 PM, Joe Perches wrote:
>> > On Fri, 2014-09-19 at 12:26 +0200, Javier Martinez Canillas wrote:
>> >> The function max77686_rtc_calculate_wday() is used to
>> >> calculate the day of the week to be filled in struct
>> >> rtc_time but that function only calculates the number
>> >> of bits shifted. So the ffs() function can be used to
>> >> find the first bit set instead of a special function.
>> > 
>> > This isn't the same logic.  Perhaps you want fls.
>> >
>> 
>> Right, the removed function has the same logic than fls() - 1 but the value
>> stored in data[RTC_WEEKDAY] is:
>> 
>> data[RTC_WEEKDAY] = 1 << tm->tm_wday;
>> 
>> so for this particular case, it doesn't matter since ffs() == fls() always.
> 
> I didn't look that far.
> 
> I just wanted to show that the logic wasn't the same.
> 

No worries, thanks a lot for your feedback. Probably it would had been good to
mention that in the commit message.

> Perhaps you can specify that ffs==fls in the changelog.
> 

I won't say I'm thrilled to do a whole re-spin of the series just to change
that ;)

Specially since I already did too many revisions and this series have been
floating around for months but is up to Andrew to decide if is worth it.

Best regards,
Javier


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