This is a note to let you know that I've just added the patch titled
iio: stm32: fix adc/trigger link error
to the 4.14-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git%3Ba=su...
The filename of the patch is: iio-stm32-fix-adc-trigger-link-error.patch and it can be found in the queue-4.14 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree, please let stable@vger.kernel.org know about it.
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
From: Arnd Bergmann arnd@arndb.de
commit 6d745ee8b5e81f3a33791e3c854fbbfd6f3e585e upstream.
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 Signed-off-by: Jonathan Cameron Jonathan.Cameron@huawei.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- include/linux/iio/timer/stm32-lptim-trigger.h | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-)
--- 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
Patches currently in stable-queue which might be from arnd@arndb.de are
queue-4.14/iio-stm32-fix-adc-trigger-link-error.patch