linux-kernel - Re: [PATCHv6 2/4] iio: adc: exynos_adc: Control special clock of ADC to support Exynos3250 ADC

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Date:	Sat, 19 Jul 2014 01:11:53 +0900
From:	Chanwoo Choi <cwchoi00@...il.com>
To:	Arnd Bergmann <arnd@...db.de>
Cc:	linux-arm-kernel <linux-arm-kernel@...ts.infradead.org>,
	Mark Rutland <mark.rutland@....com>,
	devicetree <devicetree@...r.kernel.org>,
	Kukjin Kim <kgene.kim@...sung.com>, pawel.moll@....com,
	ijc+devicetree@...lion.org.uk, linux-iio@...r.kernel.org,
	Tomasz Figa <t.figa@...sung.com>, rdunlap@...radead.org,
	linux-doc@...r.kernel.org,
	linux-kernel <linux-kernel@...r.kernel.org>,
	Rob Herring <robh+dt@...nel.org>,
	Chanwoo Choi <cw00.choi@...sung.com>,
	Kyungmin Park <kyungmin.park@...sung.com>,
	linux-samsung-soc <linux-samsung-soc@...r.kernel.org>,
	galak@...eaurora.org, naveen krishna <ch.naveen@...sung.com>,
	jic23@...nel.org
Subject: Re: [PATCHv6 2/4] iio: adc: exynos_adc: Control special clock of ADC
 to support Exynos3250 ADC

On Sat, Jul 19, 2014 at 12:23 AM, Arnd Bergmann <arnd@...db.de> wrote:
> On Saturday 19 July 2014 00:15:35 Chanwoo Choi wrote:
>> On Fri, Jul 18, 2014 at 8:14 PM, Arnd Bergmann <arnd@...db.de> wrote:
>> > On Friday 18 July 2014 19:00:48 Chanwoo Choi wrote:
>> >> On 07/18/2014 06:47 PM, Arnd Bergmann wrote:
>> >> >
>> >> > Further, why is it called "sclk_adc" rather than just "sclk"?
>> >>
>> >> The sclk means 'special clock' in Exynos TRM. Exynos SoC has varisou sclk clocks.
>> >> 'sclk_adc' is only used for ADC IP.
>> >
>> > But that sounds like sclk_adc is the name of the global name
>> > of the clock signal coming out of the clock controller.
>> >
>> > I still think it would be best to name it 'sclk' as the input
>> > for the adc. It shouldn't rely on a particular name of the
>> > clock controller.
>>
>> I think 'sclk' is too common name. 'sclk' don't include specific device name.
>> As I know, usual clock name includes the name of IP or includes the
>> specific meaning for each IP.
>
> No, normally it does not include the name of the IP, that's my whole point.
> Including the name of the IP is completely pointless because that is
> implied by the fact that it's being used by that particular IP.
>
> Ideally you would find the data sheet for the ADC IP block and figure
> out what this clock is used for, then find the right name for that.

I mentioned the meaning of clocks ('adc', 'sclk_adc') as following in
patch description.
But, you think that need the more proper name instead of 'sclk_adc' to mean the
correct operation of 'sclk_adc'. I'll check once again the meaning of
'sclk_adc' in data sheet
and renaming it.

  Exynos3250/Exynos4/Exynos5 has 'adc' clock as following:
  - 'adc' clock: bus clock for ADC

  Exynos3250 has additional 'sclk_adc' clock as following:
  - 'sclk_adc' clock: special clock for ADC which provide clock to internal ADC

> In a lot of cases, we are actually better off not naming the clocks
> at all but simply enumerating them if nobody knows what they are good
> for. In that case, you would simply have the first clock and the second
> clock of the ADC part and enable them both.

Thanks for your  review.
Chanwoo Choi
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