Re: [PATCH v3 1/2] gpio: dt-bindings: add parsing of loongson gpio offset
From: Yinbo Zhu
Date: Sun Aug 13 2023 - 23:41:03 EST
在 2023/8/11 下午10:25, Bartosz Golaszewski 写道:
On Thu, Aug 10, 2023 at 8:19 AM Yinbo Zhu <zhuyinbo@xxxxxxxxxxx> 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