Message-ID: <da83af87-6c70-8b00-b602-342a9274f81f@st.com>
Date:   Mon, 27 Nov 2017 10:09:47 +0100
From:   Fabrice Gasnier <fabrice.gasnier@...com>
To:     Jonathan Cameron <jic23@...nel.org>,
        Jonathan Cameron <Jonathan.Cameron@...wei.com>
CC:     Alexandre Torgue <alexandre.torgue@...com>,
        Arnd Bergmann <arnd@...db.de>, <linux-iio@...r.kernel.org>,
        <linux-kernel@...r.kernel.org>,
        <linux-arm-kernel@...ts.infradead.org>
Subject: Re: [PATCH] iio: stm32: fix adc/trigger link error

On 09/25/2017 07:26 PM, Jonathan Cameron wrote:
> On Mon, 25 Sep 2017 11:16:04 +0100
> Jonathan Cameron <Jonathan.Cameron@...wei.com> wrote:
> 
>> On Mon, 25 Sep 2017 11:54:06 +0200
>> Fabrice Gasnier <fabrice.gasnier@...com> wrote:
>>
>>> On 09/10/2017 06:00 PM, Jonathan Cameron wrote:  
>>>> On Wed, 6 Sep 2017 18:16:33 +0200
>>>> Fabrice Gasnier <fabrice.gasnier@...com> wrote:
>>>>     
>>>>> On 09/06/2017 02:56 PM, Arnd Bergmann wrote:    
>>>>>> The ADC driver can trigger on either the timer or the lptim
>>>>>> trigger, but it only uses a Kconfig 'select' statement
>>>>>> to ensure that the first of the two is present. When the lptim
>>>>>> trigger is enabled as a loadable module, and the adc driver
>>>>>> is built-in, we now get a link error:
>>>>>>
>>>>>> drivers/iio/adc/stm32-adc.o: In function `stm32_adc_get_trig_extsel':
>>>>>> stm32-adc.c:(.text+0x4e0): undefined reference to `is_stm32_lptim_trigger'
>>>>>>
>>>>>> We could use a second 'select' statement and always have both
>>>>>> trigger drivers enabled when the adc driver is, but it seems that
>>>>>> the lptimer trigger was intentionally left optional, so it seems
>>>>>> better to keep it that way.      
>>>>> Hi Arnd,
>>>>>
>>>>> This is correct, not all stm32 have this hardware.    
>>>>>>
>>>>>> This adds a hack to use 'IS_REACHABLE()' rather than 'IS_ENABLED()',
>>>>>> which avoids the link error, but instead leads to the lptimer trigger
>>>>>> not being used in the broken configuration. I've added a runtime
>>>>>> warning for this case to help users figure out what they did wrong
>>>>>> if this should ever be done by accident.
>>>>>>
>>>>>> Fixes: f0b638a7f6db ("iio: adc: stm32: add support for lptimer triggers")
>>>>>> Signed-off-by: Arnd Bergmann <arnd@...db.de>      
>>>>> Tested-by: Fabrice Gasnier <fabrice.gasnier@...com>    
>>>>
>>>> This may take me a few weeks to pick up.  I don't want to
>>>> pull the mfd immutable branch in just to have this fix, so this will
>>>> get sorted after rc1 is out.
>>>>
>>>> As ever, poke me if it looks like I've forgotten about it.    
>>>
>>> Hi Jonathan,
>>>
>>> Di you apply this one?  
>>
>> I think I still need to rebase my branch. Greg took my fixes pull this morning
>> so I can fast forward that branch next time I'm on the right PC and then pick
>> this up.
>>
>> Thanks for the reminder.
> 
> Applied to the fixes-togreg branch of iio.git.

Hi Jonathan,

Sorry to raise this again. Maybe I missed something, but I can't find
this fix on recent tag (4.15-rc1). Do you know if this patch from Arnd
is on its way in ?

Please kindly let me know.
BR,
Fabrice
> 
> Thanks,
> 
> Jonathan
>>
>> Jonathan
>>
>>>
>>> Thanks,
>>> Best Regards,
>>> Fabrice  
>>>> Sorry for the delay!
>>>>
>>>> Jonathan
>>>>     
>>>>>
>>>>> Many thanks for the fix,
>>>>> Best Regards,
>>>>> Fabrice    
>>>>>> ---
>>>>>>  include/linux/iio/timer/stm32-lptim-trigger.h | 5 ++++-
>>>>>>  1 file changed, 4 insertions(+), 1 deletion(-)
>>>>>>
>>>>>> diff --git a/include/linux/iio/timer/stm32-lptim-trigger.h b/include/linux/iio/timer/stm32-lptim-trigger.h
>>>>>> index 34d59bfdce2d..464458d20b16 100644
>>>>>> --- a/include/linux/iio/timer/stm32-lptim-trigger.h
>>>>>> +++ b/include/linux/iio/timer/stm32-lptim-trigger.h
>>>>>> @@ -16,11 +16,14 @@
>>>>>>  #define LPTIM2_OUT	"lptim2_out"
>>>>>>  #define LPTIM3_OUT	"lptim3_out"
>>>>>>  
>>>>>> -#if IS_ENABLED(CONFIG_IIO_STM32_LPTIMER_TRIGGER)
>>>>>> +#if IS_REACHABLE(CONFIG_IIO_STM32_LPTIMER_TRIGGER)
>>>>>>  bool is_stm32_lptim_trigger(struct iio_trigger *trig);
>>>>>>  #else
>>>>>>  static inline bool is_stm32_lptim_trigger(struct iio_trigger *trig)
>>>>>>  {
>>>>>> +#if IS_ENABLED(CONFIG_IIO_STM32_LPTIMER_TRIGGER)
>>>>>> +	pr_warn_once("stm32 lptim_trigger not linked in\n");
>>>>>> +#endif
>>>>>>  	return false;
>>>>>>  }
>>>>>>  #endif
>>>>>>       
>>>>> --
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>>>
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