From 5919fb97dd85e7ee200ab60151244cca62f61368 Mon Sep 17 00:00:00 2001 From: Nicolas Boullis Date: Sun, 10 Apr 2016 13:23:05 +0200 Subject: [PATCH] rtc: ds1307: ensure that any pending alarm is cleared before a new alarm is enabled MIME-Version: 1.0 Content-Type: text/plain; charset=utf8 Content-Transfer-Encoding: 8bit If a previously-set alarm was disabled and then triggered, it may still be pending when a new alarm is configured. Then, if the alarm is enabled before the pending alarm is cleared, then an interrupt is immediately raised. Unfortunately, when the alarm is cleared and enabled during the same I²C block write, the chip (at least the DS1339 I have) considers that the alarm is enabled before it is cleared, and raises an interrupt. This patch ensures that the pending alarm is cleared before the alarm is enabled. Signed-off-by: Nicolas Boullis Signed-off-by: Alexandre Belloni --- drivers/rtc/rtc-ds1307.c | 13 ++++++++----- 1 file changed, 8 insertions(+), 5 deletions(-) diff --git a/drivers/rtc/rtc-ds1307.c b/drivers/rtc/rtc-ds1307.c index eed5c06bf624..f027a95a943f 100644 --- a/drivers/rtc/rtc-ds1307.c +++ b/drivers/rtc/rtc-ds1307.c @@ -542,12 +542,8 @@ static int ds1337_set_alarm(struct device *dev, struct rtc_wkalrm *t) buf[5] = 0; buf[6] = 0; - /* optionally enable ALARM1 */ + /* disable alarms */ buf[7] = control & ~(DS1337_BIT_A1IE | DS1337_BIT_A2IE); - if (t->enabled) { - dev_dbg(dev, "alarm IRQ armed\n"); - buf[7] |= DS1337_BIT_A1IE; /* only ALARM1 is used */ - } buf[8] = status & ~(DS1337_BIT_A1I | DS1337_BIT_A2I); ret = ds1307->write_block_data(client, @@ -557,6 +553,13 @@ static int ds1337_set_alarm(struct device *dev, struct rtc_wkalrm *t) return ret; } + /* optionally enable ALARM1 */ + if (t->enabled) { + dev_dbg(dev, "alarm IRQ armed\n"); + buf[7] |= DS1337_BIT_A1IE; /* only ALARM1 is used */ + i2c_smbus_write_byte_data(client, DS1337_REG_CONTROL, buf[7]); + } + return 0; } -- 2.34.1