linux-kernel - Re: [PATCH v5 7/7] ARM: dts: sun9i: Switch to the AC100 RTC clock outputs for osc32k

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Date:	Tue, 12 Jul 2016 10:02:55 +0800
From:	Chen-Yu Tsai <wens@...e.org>
To:	Maxime Ripard <maxime.ripard@...e-electrons.com>
Cc:	Chen-Yu Tsai <wens@...e.org>, Lee Jones <lee.jones@...aro.org>,
	Alessandro Zummo <a.zummo@...ertech.it>,
	Alexandre Belloni <alexandre.belloni@...e-electrons.com>,
	linux-kernel <linux-kernel@...r.kernel.org>,
	rtc-linux@...glegroups.com,
	devicetree <devicetree@...r.kernel.org>,
	linux-arm-kernel <linux-arm-kernel@...ts.infradead.org>
Subject: Re: [PATCH v5 7/7] ARM: dts: sun9i: Switch to the AC100 RTC clock
 outputs for osc32k

On Mon, Jul 11, 2016 at 2:50 PM, Maxime Ripard
<maxime.ripard@...e-electrons.com> wrote:
> Hi,
>
> On Fri, Jul 08, 2016 at 10:33:42PM +0800, Chen-Yu Tsai wrote:
>> The 32.768 kHz clock inside the A80 SoC is fed from an external source,
>> typically the AC100 RTC module.
>>
>> Make the osc32k placeholder a fixed-factor clock so board dts files can
>> specify its source.
>>
>> Signed-off-by: Chen-Yu Tsai <wens@...e.org>
>> ---
>> Changes since v4: none
>> Changes since v3: none
>> Changes since v2: none
>> Changes since v1: none
>> ---
>>  arch/arm/boot/dts/sun9i-a80-cubieboard4.dts | 5 +++++
>>  arch/arm/boot/dts/sun9i-a80-optimus.dts     | 5 +++++
>>  arch/arm/boot/dts/sun9i-a80.dtsi            | 9 +++------
>>  3 files changed, 13 insertions(+), 6 deletions(-)
>>
>> diff --git a/arch/arm/boot/dts/sun9i-a80-cubieboard4.dts b/arch/arm/boot/dts/sun9i-a80-cubieboard4.dts
>> index cf2f4b72a841..04b014603659 100644
>> --- a/arch/arm/boot/dts/sun9i-a80-cubieboard4.dts
>> +++ b/arch/arm/boot/dts/sun9i-a80-cubieboard4.dts
>> @@ -103,6 +103,11 @@
>>       allwinner,drive = <SUN4I_PINCTRL_40_MA>;
>>  };
>>
>> +&osc32k {
>> +     /* osc32k input is from AC100 */
>> +     clocks = <&ac100_rtc 0>;
>> +};
>> +
>
> I'm guessing that an unresolved dependency when the driver has not
> loaded yet, or is not even compiled ?
>
> How is it working then?

I assume the clk framework will leave it unresolved and unusable.
Also it seems that none of existing clks use it as a parent by
default. I will need to check the remaining unimplemented ones
though.

ChenYu