On 13/11/2018 12:32:50+0100, Marek Szyprowski wrote: > (RTC,ALM)YEAR registers of Exynos built-in RTC device contains 3 BCD > characters. s3c-rtc driver uses only 2 lower of them and supports years > from 2000..2099 range. The third BCD value is typically set to 0, but it > looks that handling of it is broken in the hardware. It sometimes > defaults to a random (even non-BCD) value. This is not an issue > for handling RTCYEAR register, because bcd2bin() properly handles only > 8bit values (2 BCD characters, the third one is skipped). The problem > is however with ALMYEAR register and proper RTC alarm operation. When > YEAREN bit is set for the configured alarm, RTC hardware triggers alarm > only when ALMYEAR and RTCYEAR matches. This usually doesn't happen > because of the random noise on the third BCD character. > > Fix this by simply skipping setting ALMYEAR register in alarm > configuration. This workaround fixes broken alarm operation on Exynos > built-in rtc device. My tests revealed that the issue happens on the > following Exynos series: 3250, 4210, 4412, 5250 and 5410. > > Signed-off-by: Marek Szyprowski <m.szyprowski@xxxxxxxxxxx> > --- > drivers/rtc/rtc-s3c.c | 6 ------ > 1 file changed, 6 deletions(-) > Applied, thanks. -- Alexandre Belloni, Bootlin Embedded Linux and Kernel engineering https://bootlin.com
