Using the ~ operator on a BIT() constant results in a large 'unsigned long'
constant that won't fit into an 'unsigned int' function argument on 64-bit
architectures, resulting in a harmless build warning in x86 allmodconfig:

drivers/rtc/rtc-stm32.c: In function 'stm32_rtc_probe':
drivers/rtc/rtc-stm32.c:651:51: error: large integer implicitly truncated to 
unsigned type [-Werror=overflow]
  regmap_update_bits(rtc->dbp, PWR_CR, PWR_CR_DBP, ~PWR_CR_DBP);

This works around the warning by adding an explict cast to 'u32', but
that is unfortunately a bit ugly and I feel there should be a better
way to do this, possibly with some changes to either the bitops.h
header or the regmap API.

Cc: Mark Brown <>
Fixes: 4e64350f42e2 ("rtc: add STM32 RTC driver")
Signed-off-by: Arnd Bergmann <>
 drivers/rtc/rtc-stm32.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/rtc/rtc-stm32.c b/drivers/rtc/rtc-stm32.c
index 8c599f52124c..05d3dc89e55f 100644
--- a/drivers/rtc/rtc-stm32.c
+++ b/drivers/rtc/rtc-stm32.c
@@ -92,7 +92,7 @@
 /* STM32_PWR_CR */
 #define PWR_CR                         0x00
 /* STM32_PWR_CR bit field */
-#define PWR_CR_DBP                     BIT(8)
+#define PWR_CR_DBP                     (u32)BIT(8)
 struct stm32_rtc {
        struct rtc_device *rtc_dev;

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