linux-kernel - Re: [PATCH linux-next v1 2/4] clk: renesas: Add binding document for AVB Counter Clock

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Date:   Thu, 22 Nov 2018 16:06:10 +0900
From:   Jiada Wang <jiada_wang@...tor.com>
To:     Stephen Boyd <sboyd@...nel.org>, <geert+renesas@...der.be>,
        <horms@...ge.net.au>, <magnus.damm@...il.com>,
        <mark.rutland@....com>, <mturquette@...libre.com>,
        <robh+dt@...nel.org>
CC:     <linux-kernel@...r.kernel.org>,
        <linux-renesas-soc@...r.kernel.org>, <linux-clk@...r.kernel.org>,
        <kuninori.morimoto.gx@...esas.com>
Subject: Re: [PATCH linux-next v1 2/4] clk: renesas: Add binding document for
 AVB Counter Clock

Hi Stephen


On 2018/11/04 12:14, Stephen Boyd wrote:
> Quoting Jiada Wang (2018-10-31 05:00:49)
>> On 2018/10/30 3:29, Stephen Boyd wrote:
>>> Quoting jiada_wang@...tor.com (2018-10-25 00:23:47)
>>>> +Required Properties:
>>>> +  - compatible: Must be "renesas,clk-avb"
>>>> +  - reg: Base address and length of the memory resource used by the AVB
>>>> +  - #clock-cells: Must be 1
>>>> +
>>>> +Example
>>>> +-------
>>>> +
>>>> +       clk_avb: avb-clock@...a011c {
>>>> +               compatible = "renesas,clk-avb";
>>>> +               reg = <0 0xec5a011c 0 0x24>;
>>> This is an odd register offset. Is this just one clk inside of a larger
>>> clk controller?
>>>
>> Yes, avb_counter clock is part of Audio Clock Generator reg: <0
>> 0xec5a0000 0 0x140>,
>> but "adg" has already been declared in R-Car GEN2/GEN3 SoC .dtsi file,
>> with reg: <0 0xec5a0000 0 0x100>,
>> which leaves <0 0xec5a0100 0 0x140> currently not used by any module.
>>
> So why can't we expand the register size in the dts file and update the
> audio clock generator driver to register this avb clock too? Presumably
> the mapping is large enough to cover the clk registers already so it is
> more of a formality to expand the register size than a requirement.
I am working on ver2 to expend register size to cover <0 0xec5a0100 0 0x140>
in audio clock generator (ADG) driver, but as provider of newly added 
"AVB_COUNTER" clock,
ADG driver also uses these clocks if necessary, so it keeps itself BUSY,
and cause ADG driver can't be unloaded.
my question is, is such use case allowed? (clock provider is also client 
of clocks).


Thanks,
Jiada