Hi,
On 10/29/20 11:59 AM, Coiby Xu wrote:
> Hi Hans,
>
> Thank you for reviewing this patch!
>
> On Thu, Oct 29, 2020 at 11:04:36AM +0100, Hans de Goede wrote:
>> Hi,
>>
>> On 10/29/20 8:41 AM, Coiby Xu wrote:
>>> SIMPLE_DEV_PM_OPS has already took good care of CONFIG_PM_CONFIG.
>>
>> No it does not, when CONFIG_PM_SLEEP is not set then the
>> SET_SYSTEM_SLEEP_PM_OPS macro which SIMPLE_DEV_PM_OPS uses
>> is a no-op, so nothing will reference xo15_sci_resume leading to
>> a compiler warning when CONFIG_PM_SLEEP is not set.
>>
>> You could drop the ifdef and add __maybe_unused to the definition
>> of xo15_sci_resume, but that feels like needless churn, best to
>> just keep this as is IMHO.
>>
>
> Actually, this is a tree-wide change by some semi-automation scripts.
> Thank you for pointing out the issue to prevent me from releasing
> another ~150 emails to flood other mailing lists.
>
> Currently there are 929 drivers has device PM callbacks,
>
> $ grep -rI "\.pm = &" --include=*.c ./|wc -l
> 929
>
> I put all files having device PM callbacks into four categories
> based on weather a file has CONFIG_PM_SLEEP or PM macro like
> SET_SYSTEM_SLEEP_PM_OPS, here are the statistics,
> 1. have both CONFIG_PM_SLEEP and PM_OPS macro: 213
> 2. have CONFIG_PM_SLEEP but no PM_OPS macro: 19
> 3. have PM macro but not CONFIG_PM_SLEEP: 347
> 4. no PM macro or CONFIG_PM_SLEEP: 302
>
> Some drivers which have PM macro but not CONFIG_PM_SLEEP like
> sound/x86/intel_hdmi_audio.c indeed use __maybe_unused to eliminate
> the compiling warning. In 2011, there's a patch proposing to remove
> ONFIG_PM altogether but an objection was turning CONFIG_PM on would
> increase the kernel size [1]. So __maybe_unused also have this issue.
I would expect the compiler to remove the unused function, it knows
it is unused, that is why __maybe_unused is necessary to suppress
the warning and compilers are pretty smart and agressive wrt remove
unnecessary code these days.
Regards,
Hans
>>> ---
>>> arch/x86/platform/olpc/olpc-xo15-sci.c | 2 --
>>> 1 file changed, 2 deletions(-)
>>>
>>> diff --git a/arch/x86/platform/olpc/olpc-xo15-sci.c b/arch/x86/platform/olpc/olpc-xo15-sci.c
>>> index 85f4638764d6..716eefd735a4 100644
>>> --- a/arch/x86/platform/olpc/olpc-xo15-sci.c
>>> +++ b/arch/x86/platform/olpc/olpc-xo15-sci.c
>>> @@ -192,7 +192,6 @@ static int xo15_sci_remove(struct acpi_device *device)
>>> return 0;
>>> }
>>>
>>> -#ifdef CONFIG_PM_SLEEP
>>> static int xo15_sci_resume(struct device *dev)
>>> {
>>> /* Enable all EC events */
>>> @@ -204,7 +203,6 @@ static int xo15_sci_resume(struct device *dev)
>>>
>>> return 0;
>>> }
>>> -#endif
>>>
>>> static SIMPLE_DEV_PM_OPS(xo15_sci_pm, NULL, xo15_sci_resume);
>>>
>>>
>>
>
> --
> Best regards,
> Coiby
>
