Re: [PATCH 7/9] dt-bindings: spi: mtk-snfi: add two timing delay property

[Krzysztof Kozlowski]

On 30/11/2022 09:18, Xiangsheng Hou (侯祥胜) wrote:
> Hi Krzysztof,
> 
> On Tue, 2022-11-29 at 08:47 +0100, Krzysztof Kozlowski wrote:
>> On 29/11/2022 03:50, Xiangsheng Hou (侯祥胜) wrote:
>>
>>>>> --- a/Documentation/devicetree/bindings/spi/mediatek,spi-mtk-
>>>>> snfi.yaml
>>>>> +++ b/Documentation/devicetree/bindings/spi/mediatek,spi-mtk-
>>>>> snfi.yaml
>>>>> @@ -55,6 +55,22 @@ properties:
>>>>>      description: device-tree node of the accompanying ECC
>>>>> engine.
>>>>>      $ref: /schemas/types.yaml#/definitions/phandle
>>>>>  
>>>>> +  rx-sample-delay:
>>>>
>>>> No, use existing property, don't invent your own stuff - missing
>>>> unit
>>>> suffix. See spi-peripheral-props.yaml.
>>>
>>> Will change to other private property. The read sample delay with
>>> MediaTek SPI NAND controller can be set with values from 0 to 47.
>>> However, it`s difficult to say the unit of each vaule, because the
>>> unit
>>> value will be difference with different chip process or different
>>> corner IC.
>>
>> Why you cannot use same formula as other SPI drivers for sample-
>> delay?
>> And divide/multiple by some factor specific to SoC, which is taken
>> from
>> driver_data?
> 
> Even for specific SoC, the unit of sample delay may be various with
> different corner IC.

Which is easy to achieve with driver_data as I said.

> Besides, whether it`s acceptable by change the property rx-sample-delay 
> and rx-latch-latency to mediatek,rx-sample-delay and mediatek,rx-latch-
> latency?

Not for sample delay, because you should use existing properties. Your
driver implementation is not usually argument to duplicate properties in
the bindings.

Best regards,
Krzysztof