Re: [PATCH 18/20] wifi: rtw88: Add rtw8821a.{c,h}

[Bitterblue Smith <rtl8821cerfe2@gmail.com>]

On 23/09/2024 08:47, Ping-Ke Shih wrote:
> Bitterblue Smith <rtl8821cerfe2@gmail.com> wrote:
>>>>>>>> +
>>>>>>>> +const struct rtw_chip_info rtw8812a_hw_spec = {
>>>>>>>
>>>>>>> Is it possible moving 8812a to individual file?
>>>>>>> Since you have rtw8812au.c and rtw8821au.c.
>>>>>>>
>>>>>>
>>>>>> I think it is possible. But most of the code is common to both chips.
>>>>>> Only the IQ calibration could be moved.
>>>>>
>>>>> Yep, depend on how much IQK code echo chip has.
>>>>>
>>>>
>>>> The IQ calibration for RTL8812AU is about 700 lines.
>>>
>>> rtw8812au  -----> (a) rtw8812a
>>>                         |
>>>                         v
>>>                   (b) rtw8821a_common  (hard to give a name)
>>>                         ^
>>>                         |
>>> rtw8821au  -----> (c) rtw8821a
>>>
>>> Put all common code to (b). IQK code in (a) or (c).
>>>
>>> I feel you have thought above picture already. What are problems we will encounter?
>>> Many export symbols? If so, how about below?
>>>
>>> rtw8812au  -----> (1) rtw8812a
>>>     +---------+
>>>               +-> (2) rtw8821a_common  (hard to give a name)
>>>     +---------+
>>> rtw8821au  -----> (3) rtw8821a
>>>
>>> Put rtw8812a_hw_spec and rtw8821a_hw_spec in (2). Only IQK code in (1) and (3)
>>> respectively, and export IQK entry only. Does it work?
>>>
>>>
>> For the name of the common module, I was thinking rtw88_88xxa.ko.
>>
>> I wonder, what is the goal? To put the code in separate kernel
>> modules, or just separate files?
> 
> I would like to reduce runtime memory. As I asked, how many IQK code are different
> from them? If you have separated and compiled them, can you share size by the
> output of 'size' command? 
> 

I separated the IQK code into two files (still just one module).
size says:

   text    data     bss     dec     hex filename
   7192      32       0    7224    1c38 rtw8821a-iqk.o
  12319      40       0   12359    3047 rtw8812a-iqk.o

This is x86_64.

>>
>> I think we can have rtw88xxa.c (common code), rtw8821a.c (IQK code,
>> rtw8821a_hw_spec, bluetooth stuff), and rtw8812a.c (IQK code,
>> rtw8812a_hw_spec, some efuse stuff, channel switching)... if these
>> three files compile into a single module, rtw88_88xxa.ko.
>>
>> If each file compiles into a module of its own, we have circular
>> dependencies: rtw8821a_hw_spec -> common code -> IQK code.
>> If *_hw_spec go in the common module, it still depends on both of
>> the other two modules, so what use is it?
> 
> If we have dependency of common code -> IQK code, we can't save runtime
> memory, because common code reference to both IQK code. So I felt
> dependency of IQK code would be rtw8812au --> IQK code as above second
> diagram. 
> 
> But if the work is complicated and save not few runtime memory, we can
> use simple design as current did. 
> 
> 

The IQK code can be separated into different modules if I duplicate
rtw8821a_ops and rtw8821a_pwr_track, and rtw8821a_phy_pwrtrack takes
a pointer to the IQK function. Then your first diagram above can work.

The tables also take up a bit of space:

  text    data     bss     dec     hex filename
  16832       0       0   16832    41c0 rtw8821a_table.o
  21552       0       0   21552    5430 rtw8812a_table.o

I don't know how many kilobytes is enough to make it worth
creating two more modules.