linux-kernel - Re: [PATCH 2/2] clk: meson-g12a: Add AO Clock controller driver

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Message-ID: <977d8010-6d82-5eac-5da5-6dbe0f73971a@amlogic.com>
Date:   Tue, 28 Aug 2018 11:35:32 +0800
From:   Jian Hu <jian.hu@...ogic.com>
To:     Jerome Brunet <jbrunet@...libre.com>,
        Neil Armstrong <narmstrong@...libre.com>
CC:     Kevin Hilman <khilman@...libre.com>,
        Carlo Caione <carlo@...one.org>, Rob Herring <robh@...nel.org>,
        Martin Blumenstingl <martin.blumenstingl@...glemail.com>,
        Michael Turquette <mturquette@...libre.com>,
        Stephen Boyd <sboyd@...nel.org>,
        Yixun Lan <yixun.lan@...ogic.com>,
        Jianxin Pan <jianxin.pan@...ogic.com>,
        <linux-clk@...r.kernel.org>, <linux-amlogic@...ts.infradead.org>,
        <linux-arm-kernel@...ts.infradead.org>,
        <linux-kernel@...r.kernel.org>, <devicetree@...r.kernel.org>
Subject: Re: [PATCH 2/2] clk: meson-g12a: Add AO Clock controller driver

Hi: Jerome

On 2018/8/27 21:07, Jerome Brunet wrote:
> On Fri, 2018-08-24 at 21:34 +0800, Jian Hu wrote:
>>>
>>
>> I am confued about aoclk81's parent clocks.
>>
>> I can not get the example of axg audio clock driver, Could you provide
>> the link? Had it merged into clk-meson.git?
> 
> Yes and mainline as well : drivers/clk/meson/axg-audio.c
> 
> Basically this driver is creating bypass input clocks (audio_pclk, mst_in[0-9],
> etc...) .
> 
> This allows to collect input clocks from DT (like any consumer should) will
> keeping constant in the controller clock tree.
> 
>>>From what I've seen of your controller drivers, the EE controller should have
> one input, the AO should have 3.
> 
> 
> 
> .
> 
I still can not get the example meaning in axg audio driver.

In 26 page of A113D_Datasheet V0.7 20170725-Baylibre.pdf,We can see the 
aoclk81 has two parents. clk81 and ao_slow_clk. I can not get 3 parents.

                          clk81|\
                        -------| \        aoclk81
src0 |\                       |  |-------------------
-----| \     ao_slow_clk      |  |
      |  |---------------------| /
-----| /                      |/
  src1|/


src0 is from xtal, if can generate 32k clock, but it is never used.
src1 is from gpio clock, It is never used. If necessary， the ao_slow_clk 
maybe described.

So why aoclk81 has 3 parents?