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SubjectRe: [PATCH 20/28] mfd: arizona: Remove #ifdef guards for PM related functions
Hi Richard,

Le lun., août 8 2022 at 10:53:54 +0100, Richard Fitzgerald
<rf@opensource.cirrus.com> a écrit :
> On 07/08/2022 15:52, Paul Cercueil wrote:
>> Only export the arizona_pm_ops if CONFIG_PM is set, but leave the
>> suspend/resume functions (and related code) outside #ifdef guards.
>>
>> If CONFIG_PM is not set, the arizona_pm_ops will be defined as
>> "static __maybe_unused", and the structure plus all the callbacks
>> will
>> be automatically dropped by the compiler.
>>
>> The advantage is then that these functions are now always compiled
>> independently of any Kconfig option, and thanks to that bugs and
>> regressions are easier to catch.
>>
>> Signed-off-by: Paul Cercueil <paul@crapouillou.net>
>> Cc: patches@opensource.cirrus.com
>> ---
>> drivers/mfd/arizona-core.c | 21 +++++++++++----------
>> drivers/mfd/arizona-i2c.c | 2 +-
>> drivers/mfd/arizona-spi.c | 2 +-
>> 3 files changed, 13 insertions(+), 12 deletions(-)
>>
>> diff --git a/drivers/mfd/arizona-core.c b/drivers/mfd/arizona-core.c
>> index cbf1dd90b70d..c1acc9521f83 100644
>> --- a/drivers/mfd/arizona-core.c
>> +++ b/drivers/mfd/arizona-core.c
>> @@ -480,7 +480,6 @@ static int wm5102_clear_write_sequencer(struct
>> arizona *arizona)
>> return 0;
>> }
>> -#ifdef CONFIG_PM
>> static int arizona_isolate_dcvdd(struct arizona *arizona)
>
> __maybe_unused?

No need. The symbols are always referenced.

>> {
>> int ret;
>> @@ -742,9 +741,7 @@ static int arizona_runtime_suspend(struct device
>> *dev)
>
> __maybe_unused?
>
>>  return 0;
>> }
>> -#endif
>> -#ifdef CONFIG_PM_SLEEP
>> static int arizona_suspend(struct device *dev)
>
> __maybe_unused?
>
>> {
>> struct arizona *arizona = dev_get_drvdata(dev);
>> @@ -784,17 +781,21 @@ static int arizona_resume(struct device *dev)
>
> __maybe_unused?
>
>>  return 0;
>> }
>> -#endif
>> +#ifndef CONFIG_PM
>> +static __maybe_unused
>> +#endif
>
> No need to ifdef a __maybe_unused.

Yes, it is needed, because the symbol is conditionally exported. If
!CONFIG_PM, we want the compiler to discard the dev_pm_ops and all the
callbacks, hence the "static __maybe_unused". That's the same trick
used in _EXPORT_DEV_PM_OPS().

(note that this patch is broken as it does not change the struct name,
in the !PM case, which causes conflicts with the .h. I'll fix in v2)

>> const struct dev_pm_ops arizona_pm_ops = {
>> - SET_RUNTIME_PM_OPS(arizona_runtime_suspend,
>> - arizona_runtime_resume,
>> - NULL)
>> - SET_SYSTEM_SLEEP_PM_OPS(arizona_suspend, arizona_resume)
>> - SET_NOIRQ_SYSTEM_SLEEP_PM_OPS(arizona_suspend_noirq,
>> - arizona_resume_noirq)
>> + RUNTIME_PM_OPS(arizona_runtime_suspend,
>> + arizona_runtime_resume,
>> + NULL)
>> + SYSTEM_SLEEP_PM_OPS(arizona_suspend, arizona_resume)
>> + NOIRQ_SYSTEM_SLEEP_PM_OPS(arizona_suspend_noirq,
>> + arizona_resume_noirq)
>> };
>> +#ifdef CONFIG_PM
>> EXPORT_SYMBOL_GPL(arizona_pm_ops);
>> +#endif
>
> This ifdeffing is ugly. Why must the structure only be exported if
> CONFIG_PM is set?

So that all the PM code is garbage-collected by the compiler if
!CONFIG_PM.

Ideally I would use something like EXPORT_SIMPLE_DEV_PM_OPS() which
would make the patch much cleaner, but it doesn't support noirq
callbacks - and that's why I suggested in the cover letter that maybe a
new PM macro can be added if this patch is deemed too messy.

Cheers,
-Paul

>>  #ifdef CONFIG_OF
>> static int arizona_of_get_core_pdata(struct arizona *arizona)
>> diff --git a/drivers/mfd/arizona-i2c.c b/drivers/mfd/arizona-i2c.c
>> index 6d83e6b9a692..8799d9183bee 100644
>> --- a/drivers/mfd/arizona-i2c.c
>> +++ b/drivers/mfd/arizona-i2c.c
>> @@ -119,7 +119,7 @@ static const struct of_device_id
>> arizona_i2c_of_match[] = {
>> static struct i2c_driver arizona_i2c_driver = {
>> .driver = {
>> .name = "arizona",
>> - .pm = &arizona_pm_ops,
>> + .pm = pm_ptr(&arizona_pm_ops),
>> .of_match_table = of_match_ptr(arizona_i2c_of_match),
>> },
>> .probe = arizona_i2c_probe,
>> diff --git a/drivers/mfd/arizona-spi.c b/drivers/mfd/arizona-spi.c
>> index 941b0267d09d..da05b966d48c 100644
>> --- a/drivers/mfd/arizona-spi.c
>> +++ b/drivers/mfd/arizona-spi.c
>> @@ -282,7 +282,7 @@ static const struct of_device_id
>> arizona_spi_of_match[] = {
>> static struct spi_driver arizona_spi_driver = {
>> .driver = {
>> .name = "arizona",
>> - .pm = &arizona_pm_ops,
>> + .pm = pm_ptr(&arizona_pm_ops),
>> .of_match_table = of_match_ptr(arizona_spi_of_match),
>> .acpi_match_table = ACPI_PTR(arizona_acpi_match),
>> },


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