This is a note to let you know that I've just added the patch titled

iio: stm32: fix adc/trigger link error

to my staging git tree which can be found at git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/staging.git in the staging-linus branch.

The patch will show up in the next release of the linux-next tree (usually sometime within the next 24 hours during the week.)

The patch will hopefully also be merged in Linus's tree for the next -rc kernel release.

If you have any questions about this process, please let me know.

From 6d745ee8b5e81f3a33791e3c854fbbfd6f3e585e Mon Sep 17 00:00:00 2001

From: Arnd Bergmann arnd@arndb.de Date: Wed, 6 Sep 2017 14:56:50 +0200 Subject: iio: stm32: fix adc/trigger link error

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.

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 Cc: Stable@vger.kernel.org Signed-off-by: Jonathan Cameron Jonathan.Cameron@huawei.com --- 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