linux-kernel - [PATCH 2/2] rtc: Refine rtc_timer_do_work() to consider other set alarm failures

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Date:	Mon,  8 Dec 2014 20:03:07 +0800
From:	Xunlei Pang <pang.xunlei@...aro.org>
To:	linux-kernel@...r.kernel.org
Cc:	rtc-linux@...glegroups.com,
	Alessandro Zummo <a.zummo@...ertech.it>,
	John Stultz <john.stultz@...aro.org>,
	Arnd Bergmann <arnd.bergmann@...aro.org>,
	Xunlei Pang <pang.xunlei@...aro.org>
Subject: [PATCH 2/2] rtc: Refine rtc_timer_do_work() to consider other set alarm failures

rtc_timer_do_work() only judges -ETIME failure of__rtc_set_alarm(),
but doesn't handle other failures like -EIO, -EBUSY, etc.

If there is a failure other than -ETIME, the next rtc_timer will stay
in the timerqueue. Then later rtc_timers will be enqueued directly because
they have a later expires time, so the alarm irq will never be programmed.

When such failures happen, this patch will retry __rtc_set_alarm(), if
still can't program the alarm time, it will remove current rtc_timer from
timerqueue and fetch next one, thus preventing it from affecting other
rtc timers.

Signed-off-by: Xunlei Pang <pang.xunlei@...aro.org>
---
 drivers/rtc/interface.c | 13 +++++++++++++
 1 file changed, 13 insertions(+)

diff --git a/drivers/rtc/interface.c b/drivers/rtc/interface.c
index af19213..77a1529 100644
--- a/drivers/rtc/interface.c
+++ b/drivers/rtc/interface.c
@@ -898,11 +898,24 @@ again:
 	if (next) {
 		struct rtc_wkalrm alarm;
 		int err;
+		int retry = 3;
+
 		alarm.time = rtc_ktime_to_tm(next->expires);
 		alarm.enabled = 1;
+reprogram:
 		err = __rtc_set_alarm(rtc, &alarm);
 		if (err == -ETIME)
 			goto again;
+		else if (err) {
+			if (retry-- > 0)
+				goto reprogram;
+
+			timer = container_of(next, struct rtc_timer, node);
+			timerqueue_del(&rtc->timerqueue, &timer->node);
+			timer->enabled = 0;
+			dev_err(&rtc->dev, "__rtc_set_alarm: err=%d\n", err);
+			goto again;
+		}
 	} else
 		rtc_alarm_disable(rtc);
 
-- 
1.9.1

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