linux-kernel - Re: [PATCH v2 3/3] clk: meson: a1: add support for Amlogic A1 clock driver

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Message-ID: <7a3f1e14-e5a5-407a-335a-eb68d3082eb9@amlogic.com>
Date:   Mon, 25 Nov 2019 21:51:39 +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>, Rob Herring <robh@...nel.org>,
        Martin Blumenstingl <martin.blumenstingl@...glemail.com>,
        Michael Turquette <mturquette@...libre.com>,
        Stephen Boyd <sboyd@...nel.org>,
        Qiufang Dai <qiufang.dai@...ogic.com>,
        Jianxin Pan <jianxin.pan@...ogic.com>,
        Victor Wan <victor.wan@...ogic.com>,
        Chandle Zou <chandle.zou@...ogic.com>,
        <linux-clk@...r.kernel.org>, <linux-amlogic@...ts.infradead.org>,
        <linux-arm-kernel@...ts.infradead.org>,
        <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v2 3/3] clk: meson: a1: add support for Amlogic A1 clock
 driver



On 2019/11/25 20:30, Jerome Brunet wrote:
> 
> On Mon 25 Nov 2019 at 13:01, Jian Hu <jian.hu@...ogic.com> wrote:
> 
>> On 2019/11/25 18:14, Jerome Brunet wrote:
>>>
>>> On Thu 21 Nov 2019 at 04:21, Jian Hu <jian.hu@...ogic.com> wrote:
>>>
>>>> Hi, Jerome
>>>>
>>>> On 2019/11/20 23:35, Jerome Brunet wrote:
>>>>>
>>>>> On Wed 20 Nov 2019 at 10:28, Jian Hu <jian.hu@...ogic.com> wrote:
>>>>>
>>>>>> Hi, jerome
>>>>>>
>>>>>> Is there any problem about fixed_pll_dco's parent_data?
>>>>>>
>>>>>> Now both name and fw_name are described in parent_data.
>>>>>
>>>>> Yes, there is a problem.  This approach is incorrect, as I've tried to
>>>>> explain a couple times already. Let me try to re-summarize why this
>>>>> approach is incorrect.
>>>>>
>>>>> Both fw_name and name should be provided when it is possible that
>>>>> the DT does not describe the input clock. IOW, it is only for controllers
>>>>> which relied on the global name so far and are now starting to describe
>>>>> the clock input in DT
>>>>>
>>>>> This is not your case.
>>>>> Your controller is new and DT will have the correct
>>>>> info
>>>>>
>>>>> You are trying work around an ordering issue by providing both fw_name
>>>>> and name. This is not correct and I'll continue to nack it.
>>>>>
>>>>> If the orphan clock is not reparented as you would expect, I suggest you
>>>>> try to look a bit further at how the reparenting of orphans is done in
>>>>> CCF and why it does not match your expectation.
>>>>>
>>>> I have debugged the handle for orphan clock in CCF, Maybe you are missing
>>>> the last email.
>>>
>>> Nope, got it the first time
>>>
>>>> Even though the clock index exit, it will get failed for the orphan clock's
>>>> parent clock due to it has not beed added to the provider.
>>>
>>> If the provider is not registered yet, of course any query to it won't
>>> work. This why I have suggested to this debug *further* :
>>>
>>> * Is the orphan reparenting done when a new provider is registered ?
>>> * If not, should it be done ? is this your problem ?
>>>
> 
> Apparently, I was not clear enough so I'll rephrase
> 
>> Yes, the orphan reparenting is done when the new provider is
>> registered.
> 
> No it is not done yet. Please check the code.
> 
> The reparenting of orphan is done only on clock registration, not on
> provider registeration. Now that clocks can be specified by DT, this
> probably needs to added.The action of reparenting the orphan is before the provider registration 
with the current code.
> 
> That is your problem.
Yes, if the provider is registered before the clock registration, it
will reparent successfully.
> 
> Please fix the underlying issue, then you can post your series again.
> 
>>
>> Reparenting the orphan will be done when each clock is registered by
>> devm_clk_hw_register. And at this time the provider has not been
>> registered. After all clocks are registered by devm_clk_hw_register, the
>> provider will be registered by devm_of_clk_add_hw_provider.
>>
>> Reparenting the orphan will fail when fw_name is added alone, the couse is
>> that devm_clk_hw_register is always running ahead of
>> devm_of_clk_add_hw_provider.
> 
> Please stop bringing the topic of "fw_name" and "name" field together, I
> told you 3 times why this is wrong. It is not going to change.
> 
>>
>> That is why it will failed to get parent for the orphan clock.
> 
> It fails because the provider is not registered when you try to reparent
> the orphan.
> 
> It shows that you should try again once the provider is registered.
> 
OK, I have exchanged the position for devm_clk_hw_register and 
devm_of_clk_add_hw_provider in meson-eeclk.c.

It reparents successfully for orphan clock.

Is is ok that put devm_of_clk_add_hw_provider ahead?

As far as I am concerned, there is no any effect.
>>
>>
>>
>>>
>>> .
>>>
> 
> .
>