From 72dd71f0dae47183efdf92279927ff26f0ed9f3f Mon Sep 17 00:00:00 2001 From: Jeffy Chen Date: Tue, 27 Feb 2018 10:50:03 +0800 Subject: rtc: cros-ec: return -ETIME when refused to set alarms in the past Since accessing a Chrome OS EC based rtc is a slow operation, there is a race window where if the alarm is set for the next second and the second ticks over right before calculating the alarm offset. In this case the current driver is setting a 0-second alarm, which would be considered as disabling alarms by the EC(EC_RTC_ALARM_CLEAR). This breaks, e.g., hwclock which relies on RTC_UIE_ON -> rtc_update_irq_enable(), which sets a 1-second alarm and expects it to fire an interrupt. So return -ETIME when the alarm is in the past, follow __rtc_set_alarm(). Signed-off-by: Jeffy Chen Reviewed-by: Brian Norris Tested-by: Brian Norris Signed-off-by: Alexandre Belloni --- drivers/rtc/rtc-cros-ec.c | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-) (limited to 'drivers/rtc/rtc-cros-ec.c') diff --git a/drivers/rtc/rtc-cros-ec.c b/drivers/rtc/rtc-cros-ec.c index f0ea6899c731..bf7ced095c94 100644 --- a/drivers/rtc/rtc-cros-ec.c +++ b/drivers/rtc/rtc-cros-ec.c @@ -197,10 +197,10 @@ static int cros_ec_rtc_set_alarm(struct device *dev, struct rtc_wkalrm *alrm) cros_ec_rtc->saved_alarm = (u32)alarm_time; } else { /* Don't set an alarm in the past. */ - if ((u32)alarm_time < current_time) - alarm_offset = EC_RTC_ALARM_CLEAR; - else - alarm_offset = (u32)alarm_time - current_time; + if ((u32)alarm_time <= current_time) + return -ETIME; + + alarm_offset = (u32)alarm_time - current_time; } ret = cros_ec_rtc_set(cros_ec, EC_CMD_RTC_SET_ALARM, alarm_offset); -- cgit