linux-kernel - [PATCH] rtc: cros-ec: return -ETIME when refused to set alarms in the past

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Date:   Sun, 25 Feb 2018 16:18:02 +0800
From:   Jeffy Chen <jeffy.chen@...k-chips.com>
To:     linux-kernel@...r.kernel.org
Cc:     zyw@...k-chips.com, briannorris@...gle.com, dianders@...gle.com,
        jwerner@...omium.org, Jeffy Chen <jeffy.chen@...k-chips.com>,
        linux-rtc@...r.kernel.org,
        Alexandre Belloni <alexandre.belloni@...tlin.com>,
        Alessandro Zummo <a.zummo@...ertech.it>
Subject: [PATCH] rtc: cros-ec: return -ETIME when refused to set alarms in the past

We have a check in __rtc_set_alarm() to return -ETIME when the alarm
is in the past.

Since accessing a Chrome OS EC based rtc is a slow operation, we should
do that check again inside of the EC rtc driver's .set_alarm() callback.

Signed-off-by: Jeffy Chen <jeffy.chen@...k-chips.com>
---

 drivers/rtc/rtc-cros-ec.c | 10 +++++-----
 1 file changed, 5 insertions(+), 5 deletions(-)

diff --git a/drivers/rtc/rtc-cros-ec.c b/drivers/rtc/rtc-cros-ec.c
index f0ea6899c731..ee0062e2d222 100644
--- a/drivers/rtc/rtc-cros-ec.c
+++ b/drivers/rtc/rtc-cros-ec.c
@@ -188,6 +188,10 @@ static int cros_ec_rtc_set_alarm(struct device *dev, struct rtc_wkalrm *alrm)
 	if (alarm_time < 0 || alarm_time > U32_MAX)
 		return -EINVAL;
 
+	/* Don't set an alarm in the past. */
+	if ((u32)alarm_time <= current_time)
+		return -ETIME;
+
 	if (!alrm->enabled) {
 		/*
 		 * If the alarm is being disabled, send an alarm
@@ -196,11 +200,7 @@ static int cros_ec_rtc_set_alarm(struct device *dev, struct rtc_wkalrm *alrm)
 		alarm_offset = EC_RTC_ALARM_CLEAR;
 		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;
+		alarm_offset = (u32)alarm_time - current_time;
 	}
 
 	ret = cros_ec_rtc_set(cros_ec, EC_CMD_RTC_SET_ALARM, alarm_offset);
-- 
2.11.0