Re: [PATCH v4 3/6] ACPI: CPPC: Add macros to generally implement registers getting and setting functions

["zhenglifeng (A)" <zhenglifeng1@huawei.com>]

On 2025/1/15 19:12, Rafael J. Wysocki wrote:

> On Wed, Jan 15, 2025 at 9:59 AM zhenglifeng (A) <zhenglifeng1@huawei.com> wrote:
>>
>> On 2025/1/15 1:58, Rafael J. Wysocki wrote:
>>
>>> On Mon, Jan 13, 2025 at 1:21 PM Lifeng Zheng <zhenglifeng1@huawei.com> wrote:
>>>>
>>>> Add CPPC_REG_VAL_READ() to implement registers getting functions.
>>>>
>>>> Add CPPC_REG_VAL_WRITE() to implement registers setting functions.
>>>>
>>>> Signed-off-by: Lifeng Zheng <zhenglifeng1@huawei.com>
>>>
>>> I don't particularly like these macros as they will generally make it
>>> harder to follow the code.
>>>
>>>> ---
>>>>  drivers/acpi/cppc_acpi.c | 14 ++++++++++++++
>>>>  1 file changed, 14 insertions(+)
>>>>
>>>> diff --git a/drivers/acpi/cppc_acpi.c b/drivers/acpi/cppc_acpi.c
>>>> index 571f94855dce..6326a1536cda 100644
>>>> --- a/drivers/acpi/cppc_acpi.c
>>>> +++ b/drivers/acpi/cppc_acpi.c
>>>> @@ -1279,6 +1279,20 @@ static int cppc_set_reg_val(int cpu, enum cppc_regs reg_idx, u64 val)
>>>>         return cpc_write(cpu, reg, val);
>>>>  }
>>>>
>>>> +#define CPPC_REG_VAL_READ(reg_name, reg_idx)           \
>>>> +int cppc_get_##reg_name(int cpu, u64 *val)             \
>>>> +{                                                      \
>>>> +       return cppc_get_reg_val(cpu, reg_idx, val);     \
>>>> +}                                                      \
>>>> +EXPORT_SYMBOL_GPL(cppc_get_##reg_name)
>>>
>>> What about if defining something like
>>>
>>> #define CPPC_READ_REG_VAL(cpu, reg_name, val)
>>> cppc_get_reg_val((cpu), CPPC_REG_IDX(reg_name), (val))
>>>
>>> (and analogously for the WRITE_ part), where CPPC_REG_IDX(reg_name) is
>>>
>>> #define CPPC_REG_IDX(reg_name)    CPPC_REG_##reg_name_IDX
>>>
>>> and there are CPPC_REG_##reg_name_IDX macros defined for all register
>>> names in use?
>>>
>>> For example
>>>
>>> #define CPPC_REG_desired_perf_IDX   DESIRED_PERF
>>
>> What about keeping these two macros but replace reg_idx with
>> CPPC_REG_IDX(reg_name)? With this, the only needed parameter for these two
>> macros is reg_name.
> 
> The problem is that looking up functions defined through macros is
> hard when somebody wants to know what they do, so I'd prefer to avoid
> doing that.

I see your point. Let's just remove these.

> 
>