linux-kernel - Re: [PATCH v3 5/8] rtc: ac100: Add clk output support

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Date:	Wed, 22 Jun 2016 18:11:55 +0800
From:	Chen-Yu Tsai <wens@...e.org>
To:	Maxime Ripard <maxime.ripard@...e-electrons.com>
Cc:	Chen-Yu Tsai <wens@...e.org>, Mark Brown <broonie@...nel.org>,
	Lee Jones <lee.jones@...aro.org>,
	Alessandro Zummo <a.zummo@...ertech.it>,
	Alexandre Belloni <alexandre.belloni@...e-electrons.com>,
	Rob Herring <robh+dt@...nel.org>,
	Pawel Moll <pawel.moll@....com>,
	Mark Rutland <mark.rutland@....com>,
	Ian Campbell <ijc+devicetree@...lion.org.uk>,
	Kumar Gala <galak@...eaurora.org>,
	Michael Turquette <mturquette@...libre.com>,
	Stephen Boyd <sboyd@...eaurora.org>,
	rtc-linux@...glegroups.com,
	linux-kernel <linux-kernel@...r.kernel.org>,
	devicetree <devicetree@...r.kernel.org>,
	linux-arm-kernel <linux-arm-kernel@...ts.infradead.org>,
	linux-clk <linux-clk@...r.kernel.org>
Subject: Re: [PATCH v3 5/8] rtc: ac100: Add clk output support

On Wed, Jun 22, 2016 at 6:02 PM, Maxime Ripard
<maxime.ripard@...e-electrons.com> wrote:
> Hi,
>
> On Mon, Jun 20, 2016 at 10:52:15AM +0800, Chen-Yu Tsai wrote:
>> +     /*
>> +      * The ADDA 4 MHz clock is from the codec side of the AC100,
>> +      * which is likely a different power domain. However, boards
>> +      * always have both sides powered on, so it is impossible to
>> +      * test this.
>> +      */
>
> If that ADDA clock is exposed by the codec, why are you putting it in
> the RTC?

The thing is it's not entirely clear that it's from the codec side.
I'm just inferring this from the name. (I'll make the comment clearer.)
The codec parts of the datasheet don't mention this clock at all.

Allwinner's SDK puts all the clocks under the RTC module. And the
are always on, so I can't really turn off the codec and see what
happens. That and I don't have an oscilloscope or logic analyzer.

Regards
ChenYu