Messages in this thread | | | Date | Mon, 08 Aug 2022 13:01:58 +0200 | From | Paul Cercueil <> | Subject | Re: [PATCH 20/28] mfd: arizona: Remove #ifdef guards for PM related functions |
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Le lun., août 8 2022 at 11:43:31 +0100, Richard Fitzgerald <rf@opensource.cirrus.com> a écrit : > On 08/08/2022 11:06, Paul Cercueil wrote: >> 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 > > Why conditionally export it? > >> !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. > > The functions will be dropped if they are not referenced. That doesn't > answer why the struct must not be exported. > > What is the aim of omitting the struct export?
The functions are always referenced by the dev_pm_ops structure. Omitting the struct export means that the struct can now be a "static __maybe_unused" symbol in the !CONFIG_PM case, and everything related to PM will be automatically removed by the compiler.
Otherwise, the symbol is exported as usual. The symbol being conditionally exported is not a problem - the struct is always referenced (as it should be) using the pm_sleep_ptr() or pm_ptr() macros.
This is basically what EXPORT_SIMPLE_DEV_PM_OPS() does by the way.
Cheers, -Paul
>> >> 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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