tree a6ffeb2cdca89a68d9979864b31e0c49efc380bf
parent 1d87951c398e35118a0fb67b287022f008513f42
author Nicolas Boullis <nboullis@debian.org> 1460287385 +0200
committer Alexandre Belloni <alexandre.belloni@free-electrons.com> 1463740431 +0200

rtc: ds1307: ensure that any pending alarm is cleared before a new alarm is enabled

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 <nboullis@debian.org>
Signed-off-by: Alexandre Belloni <alexandre.belloni@free-electrons.com>