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SubjectRe: [PATCH v3 1/2] gpio: dt-bindings: add parsing of loongson gpio offset
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在 2023/8/11 下午10:25, Bartosz Golaszewski 写道:
> On Thu, Aug 10, 2023 at 8:19 AM Yinbo Zhu <zhuyinbo@loongson.cn> wrote:
>>
>>
>>
>> 在 2023/8/9 下午11:39, Conor Dooley 写道:
>>> On Wed, Aug 09, 2023 at 03:47:55PM +0800, Yinbo Zhu wrote:
>>>> 在 2023/8/8 下午8:05, Conor Dooley 写道:
>>>>> On Mon, Aug 07, 2023 at 03:40:42PM +0800, Yinbo Zhu wrote:
>>>
>>>>>> + loongson,gpio-ctrl-mode:
>>>>>> + $ref: /schemas/types.yaml#/definitions/uint32
>>>>>> + description:
>>>>>> + This option indicate this GPIO control mode, where '0' represents
>>>>>> + bit control mode and '1' represents byte control mode.
>>>>>
>>>>> How is one supposed to know which of these modes to use?
>>>>
>>>>
>>>> Byte mode is to access by byte, such as gpio3, the base address of the
>>>> gpio controller is offset by 3 bytes as the access address of gpio3.
>>>>
>>>> The bit mode is the normal mode that like other platform gpio and it is
>>>> to access by bit.
>>>>
>>>> If both modes are supported, it is recommended to prioritize using byte
>>>> mode that according to spec.
>>>
>>> So, sounds like this property should instead be a boolean that notes
>>> whether the hardware supports the mode or not, rather than the current
>>> enum used to determine software policy.
>>
>>
>> okay, I got it, I will use boolean,
>>
>
> Why do you want to put it into device-tree so badly? This is not the
> first driver that would have of_match_data for different variants
> where you can have a structure that would keep offsets for different
> models. It's not like you will have hundreds of "compatible" chips
> anyway, most likely just a few?


Using this ways that put offset property into device-tree that can be
compatible with future GPIO chips without the need to modify drivers,
such as more 2K chips in the future, but use of_match_data and data
field of_device_id, which every time a new SoC is released, the GPIO
driver needs to be modified once, which is not friendly to us.

Thanks,
Yinbo

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