linux-kernel - Re: [PATCH 2/8] dt-bindings: clock: stm32mp1: describes clocks if "st,stm32mp1-rcc-secure"

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Date:   Mon, 25 Apr 2022 21:35:13 +0200
From:   Marek Vasut <marex@...x.de>
To:     Rob Herring <robh@...nel.org>
Cc:     Alexandre Torgue <alexandre.torgue@...s.st.com>, arnd@...db.de,
        Krzysztof Kozlowski <krzk+dt@...nel.org>, soc@...nel.org,
        Stephen Boyd <sboyd@...nel.org>,
        Philipp Zabel <p.zabel@...gutronix.de>,
        linux-arm-kernel@...ts.infradead.org, devicetree@...r.kernel.org,
        linux-stm32@...md-mailman.stormreply.com,
        linux-kernel@...r.kernel.org,
        Ahmad Fatoum <a.fatoum@...gutronix.de>, etienne.carriere@...com
Subject: Re: [PATCH 2/8] dt-bindings: clock: stm32mp1: describes clocks if
 "st,stm32mp1-rcc-secure"

On 4/25/22 21:11, Rob Herring wrote:
> On Fri, Apr 22, 2022 at 06:31:25PM +0200, Marek Vasut wrote:
>> On 4/22/22 17:09, Alexandre Torgue wrote:
>>> In case of "st,stm32mp1-rcc-secure" (stm32mp1 clock driver with RCC
>>> security support hardened), "clocks" and "clock-names" describe oscillators
>>> and are required.
>>>
>>> Signed-off-by: Alexandre Torgue <alexandre.torgue@...s.st.com>
>>>
>>> diff --git a/Documentation/devicetree/bindings/clock/st,stm32mp1-rcc.yaml b/Documentation/devicetree/bindings/clock/st,stm32mp1-rcc.yaml
>>> index 7a251264582d..bb0e0b92e907 100644
>>> --- a/Documentation/devicetree/bindings/clock/st,stm32mp1-rcc.yaml
>>> +++ b/Documentation/devicetree/bindings/clock/st,stm32mp1-rcc.yaml
>>> @@ -58,14 +58,8 @@ properties:
>>>              - st,stm32mp1-rcc-secure
>>>              - st,stm32mp1-rcc
>>>          - const: syscon
>>> -
>>> -  clocks:
>>> -    description:
>>> -      Specifies the external RX clock for ethernet MAC.
>>> -    maxItems: 1
>>> -
>>> -  clock-names:
>>> -    const: ETH_RX_CLK/ETH_REF_CLK
>>> +  clocks: true
>>> +  clock-names: true
>>
>> It looks like this should rather be a property than a compatible string --
>> the compatible string is used by the OS to determine which hardware is
>> represented by a node, but here it is the same hardware in either case,
>> "st,stm32mp1-rcc" and "st,stm32mp1-rcc-secure", it is still the same
>> STM32MP1 RCC block, just configured differently by some bootloader stage.
>>
>> So why not just add one-liner property of the RCC block like ?
>> st,rcc-in-secure-configuration
> 
> Because using compatible was already decided.

I see ... may I ask why compatible is OK in this case even though this 
is encoding a policy (secure/non-secure configuration of the same clock 
IP) into DT ?