On 7/11/2015 10:59 AM, Larry Finger wrote:
On a Winbook TW100 BayTrail tablet, kernel 4.0 and later do not create /dev/rtc0 when CONFIG_PINCTRL_BAYTRAIL is set in the configuration. Removing this option from the
config creates a real-time clock; however, it is no longer possible to get the tablet to sleep using the power button. Only complete shutdown works.
This problem was bisected to the following commit:
in "hardware reduced mode" (e.g. tablets) on Baytrail the RTC is not actually enabled/initialized by the firmware; talking to it may appear to work but it's really not
a good idea (and breaks things likes suspend/resume etc).