SIMPLE_DEV_PM_OPS has already took good care of CONFIG_PM_CONFIG.
Signed-off-by: Coiby Xu <[email protected]>
---
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);
--
2.28.0
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.
Also s/CONFIG_PM_CONFIG/CONFIG_PM_SLEEP/ in the commit message.
Regards,
Hans
>
> Signed-off-by: Coiby Xu <[email protected]>
> ---
> 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);
>
>
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 made a mistake when I thought PM macros like SIMPLE_DEV_PM_OPS
didn't have this issue). What do you think? Btw, It's easy for me to
add CONFIG_PM_SLEEP for those drivers have PM macro but not
CONFIG_PM_SLEEP since I have already written the necessary automation
scripts.
[1] https://lists.linux-foundation.org/pipermail/linux-pm/2011-February/030215.html
>Also s/CONFIG_PM_CONFIG/CONFIG_PM_SLEEP/ in the commit message.
>
Thank you for pointing out the typo. I've written some scripts to
automate the whole process from changing code to submitting patches.
Somehow there is still this issue.
>Regards,
>
>Hans
>
>
>>
>> Signed-off-by: Coiby Xu <[email protected]>
>> ---
>> 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
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
>
On Thu, Oct 29, 2020 at 12:09:23PM +0100, Hans de Goede wrote:
>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.
>
Then __maybe_unused is a good solution and there's also convincing
reason to prefer __maybe_unused over CONFIG_PM_SLEEP according to
Arnd Bergmann [2],
> > By and large, drivers handle this by using a CONFIG_PM_SLEEP ifdef.
> >
> > Unless you can make an extremely convincing argument why not to do
> > so here, I'd like you to handle it that way instead.
>
> [adding linux-pm to Cc]
>
> The main reason is that everyone gets the #ifdef wrong, I run into
> half a dozen new build regressions with linux-next every week on
> average, the typical problems being:
>
> - testing CONFIG_PM_SLEEP instead of CONFIG_PM, leading to an unused
> function warning
> - testing CONFIG_PM instead of CONFIG_PM_SLEEP, leading to a build
> failure
> - calling a function outside of the #ifdef only from inside an
> otherwise correct #ifdef, again leading to an unused function
> warning
> - causing a warning inside of the #ifdef but only testing if that
> is disabled, leading to a problem if the macro is set (this is
> rare these days for CONFIG_PM as that is normally enabled)
>
> Using __maybe_unused avoids all of the above.
>Regards,
>
>Hans
>
[2] https://lore.kernel.org/patchwork/comment/919944/
--
Best regards,
Coiby
Hi,
On 10/29/20 3:16 PM, Coiby Xu wrote:
> On Thu, Oct 29, 2020 at 12:09:23PM +0100, Hans de Goede wrote:
>> 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.
>>
> Then __maybe_unused is a good solution and there's also convincing
> reason to prefer __maybe_unused over CONFIG_PM_SLEEP according to
> Arnd Bergmann [2],
Ok, I would be happy to merge a patch for this which drops the #ifdef-s
and adds a __maybe_unused.
Regards,
Hans