Re: [PATCH v2] ahci: st: Switch from CONFIG_PM_SLEEP guards to pm_sleep_ptr()

[Damien Le Moal <dlemoal@kernel.org>]

On 1/10/25 20:23, Niklas Cassel wrote:
>>> -#ifdef CONFIG_PM_SLEEP
>>>  static int st_ahci_suspend(struct device *dev)
>>>  {
>>>  	struct ata_host *host = dev_get_drvdata(dev);
>>> @@ -221,9 +220,8 @@ static int st_ahci_resume(struct device *dev)
>>>  
>>>  	return ahci_platform_resume_host(dev);
>>>  }
>>> -#endif
>>
>> I do not think you can remove the ifdef here. Otherwise, there is going to be a
>> compilation warning when CONFIG_PM_SLEEP is not enabled. No ?
> 
> Look at the pm_sleep_ptr macro:
> include/linux/pm.h:#define pm_sleep_ptr(_ptr) PTR_IF(IS_ENABLED(CONFIG_PM_SLEEP), (_ptr))
> 
> I would expect the function should be optimized out by the compiler
> using dead code elimination.

Indeed. Just tried and no warning. I was expecting a "defined but not used"
warning, but none showed up. So all good.

> Raphael, perhaps you could show the before and after output
> using ./scripts/bloat-o-meter ?
> (When the config is not enabled: before and after your patch.)

No need to do that I guess. But there are 17 other ata driver that set .pm
operations. What about these ? Don't they need the same treatment as ahci_st ?
15 of these also use SIMPLE_DEV_PM_OPS() which can be replaced with
DEFINE_SIMPLE_DEV_PM_OPS() also, no ?

Do you want us to do that cleanup ? (fine with me).

-- 
Damien Le Moal
Western Digital Research