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Message-ID: <f0a8c3fd-8013-0f7f-b7f8-5e9e85395543@gmail.com>
Date:   Mon, 6 Jun 2022 16:39:06 +0800
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From:   Potin Lai <potin.lai.pt@gmail.com>
Subject: Re: [PATCH v2 2/2] dt-bindings: aspeed-i2c: add properties for manual
 clock setting
To:     Rob Herring <robh@kernel.org>
Cc:     Brendan Higgins <brendanhiggins@google.com>,
        Benjamin Herrenschmidt <benh@kernel.crashing.org>,
        Joel Stanley <joel@jms.id.au>,
        Andrew Jeffery <andrew@aj.id.au>,
        Rayn Chen <rayn_chen@aspeedtech.com>,
        Patrick Williams <patrick@stwcx.xyz>,
        Potin Lai <potin.lai@quantatw.com>, linux-i2c@vger.kernel.org,
        devicetree@vger.kernel.org, linux-arm-kernel@lists.infradead.org,
        linux-aspeed@lists.ozlabs.org, linux-kernel@vger.kernel.org
References: <20220601041512.21484-1-potin.lai.pt@gmail.com>
 <20220601041512.21484-3-potin.lai.pt@gmail.com>
 <20220605214700.GA3558088-robh@kernel.org>
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Rob Herring 於 2022/6/6 上午 05:47 寫道:
> On Wed, Jun 01, 2022 at 12:15:12PM +0800, Potin Lai wrote:
>> Add following properties for manual tuning clock divisor and cycle of
>> hign/low pulse witdh.
>>
>> * aspeed,i2c-manual-clk: Enable aspeed i2c clock manual setting
>> * aspeed,i2c-base-clk-div: Base Clock divisor (tBaseClk)
>> * aspeed,i2c-clk-high-cycle: Cycles of clock-high pulse (tClkHigh)
>> * aspeed,i2c-clk-low-cycle: Cycles of clock-low pulse (tClkLow)
>>
>> Signed-off-by: Potin Lai <potin.lai.pt@gmail.com>
>> ---
>>  .../devicetree/bindings/i2c/aspeed,i2c.yaml   | 44 +++++++++++++++++++
>>  1 file changed, 44 insertions(+)
>>
>> diff --git a/Documentation/devicetree/bindings/i2c/aspeed,i2c.yaml b/Documentation/devicetree/bindings/i2c/aspeed,i2c.yaml
>> index ea643e6c3ef5..e2f67fe2aa0c 100644
>> --- a/Documentation/devicetree/bindings/i2c/aspeed,i2c.yaml
>> +++ b/Documentation/devicetree/bindings/i2c/aspeed,i2c.yaml
>> @@ -12,6 +12,28 @@ maintainers:
>>  allOf:
>>    - $ref: /schemas/i2c/i2c-controller.yaml#
>>  
>> +  - if:
>> +      properties:
>> +        compatible:
>> +          const: st,stm32-uart
> stm32 uart?
Sorry, I will remove it.
>> +
>> +    then:
>> +      properties:
>> +        aspeed,i2c-clk-high-cycle:
>> +          maximum: 8
>> +        aspeed,i2c-clk-low-cycle:
>> +          maximum: 8
>> +
>> +  - if:
>> +      required:
>> +        - aspeed,i2c-manual-clk
>> +
>> +    then:
>> +      required:
>> +        - aspeed,i2c-base-clk-div
>> +        - aspeed,i2c-clk-high-cycle
>> +        - aspeed,i2c-clk-low-cycle
> 'dependencies' can better express this than an if/then.
>
> However, I think this should all be done in a common way.
>
>> +
>>  properties:
>>    compatible:
>>      enum:
>> @@ -49,6 +71,28 @@ properties:
>>      description:
>>        states that there is another master active on this bus
>>  
>> +  aspeed,i2c-manual-clk:
>> +    type: boolean
>> +    description: enable manual clock setting
> No need for this as presence of the other properties can determine this.
>
>> +
>> +  aspeed,i2c-base-clk-div:
>> +    $ref: /schemas/types.yaml#/definitions/uint32
>> +    enum: [1, 2, 4, 8, 16, 32, 64, 128, 256, 512, 1024, 2048, 4096, 8192,
>> +           16384, 32768]
>> +    description: base clock divisor
> Specify the i2c bus frequency and calculate the divider.
>
>> +
>> +  aspeed,i2c-clk-high-cycle:
>> +    $ref: /schemas/types.yaml#/definitions/uint32
>> +    minimum: 1
>> +    maximum: 16
>> +    description: cycles of master clock-high pulse width
>> +
>> +  aspeed,i2c-clk-low-cycle:
>> +    $ref: /schemas/types.yaml#/definitions/uint32
>> +    minimum: 1
>> +    maximum: 16
>> +    description: cycles of master clock-low pulse width
> These 2 should be common. I think you just need a single property 
> expressing duty cycle.
>
> Rob

Got it, thank you for the suggestion of duty cycle.
I will use duty cycle for next version.

Potin