[PATCH] iio: stm32: fix adc/trigger link error
From: Fabrice Gasnier <hidden>
Date: 2017-09-06 16:17:28
Also in:
linux-iio, lkml
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@arndb.de>Tested-by: Fabrice Gasnier <redacted> Many thanks for the fix, Best Regards, Fabrice
quoted hunk ↗ jump to hunk
--- 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