linux-kernel - Re: [PATCH 1/3] spi: dt-bindings: add doc for Amlogic A113L2 SFC

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Message-ID: <017a4d15-286d-4e0a-89ff-f658009a6de6@kernel.org>
Date: Wed, 13 Aug 2025 18:19:34 +0200
From: Krzysztof Kozlowski <krzk@...nel.org>
To: Xianwei Zhao <xianwei.zhao@...ogic.com>
Cc: Mark Brown <broonie@...nel.org>, Rob Herring <robh@...nel.org>,
 Krzysztof Kozlowski <krzk+dt@...nel.org>, Conor Dooley
 <conor+dt@...nel.org>, Liang Yang <liang.yang@...ogic.com>,
 Feng Chen <feng.chen@...ogic.com>, linux-spi@...r.kernel.org,
 devicetree@...r.kernel.org, linux-kernel@...r.kernel.org,
 linux-amlogic@...ts.infradead.org
Subject: Re: [PATCH 1/3] spi: dt-bindings: add doc for Amlogic A113L2 SFC

On 13/08/2025 11:34, Xianwei Zhao wrote:
> Hi Krzysztof,
>     Thanks  for your reply.
> 
> On 2025/8/13 15:36, Krzysztof Kozlowski wrote:
>> [ EXTERNAL EMAIL ]
>>
>> On 13/08/2025 08:13, Xianwei Zhao wrote:
>>>>> +allOf:
>>>>> +  - $ref: /schemas/spi/spi-controller.yaml#
>>>>> +
>>>>> +properties:
>>>>> +  compatible:
>>>>> +    const: amlogic,a4-spifc
>>>>> +
>>>>> +  reg:
>>>>> +    items:
>>>>> +      - description: core registers
>>>>> +      - description: parent clk control registers
>>>>
>>>> Why are you poking to parent node or to clock registers? This looks like
>>>> mixing up device address spaces.
>>>>
>>>
>>> The SPIFC bus clock multiplexes EMMC modules, so the corresponding
>>> frequency division register is also in EMMC module. The SPIFC and the
>>> EMMC modules cannot be used simultaneously.
>>
>> Then obviously you cannot put here EMMC or parent registers.
>>
>> It looks really like you miss proper hardware representation.
>>
> 
> It does seem a bit unusual. However, in our hardware design, EMMC and 
> SFC modules are integrated, and they share common resources such as the 
> clock and I/O pins .They are mutually exclusive.
> 

How did you express it in DT? This looks similar to serial engines and
such are not implemented independently.

> Here, I'll modify the register description. Do you think it's feasible

No, because it changes nothing... Clock provider pokes clock divider
registers. Not clock consumer.

Best regards,
Krzysztof