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| /linux/drivers/rtc/ |
| H A D | rtc-msm6242.c | diff 32c4d9e8a4eb286674dc1a3b93d51d791c7f645e Sat Nov 16 12:46:20 CET 2019 Kars de Jong <jongk@linux-m68k.org> rtc: msm6242: Remove unneeded msm6242_set()/msm6242_clear() functions
The msm6242_set()/msm6242_clear() functions are used when writing to Control
Register D to set or clear the HOLD bit when reading the current time from
the RTC.
Doing this with a read-modify-write cycle will potentially clear an
interrupt condition which occurs between the read and the write.
The datasheet states the following about this:
When writing the HOLD or 30 second adjust bits of register D, it is
necessary to write the IRQ FLAG bit to a "1".
Since the only other bits in the register are the 30 second adjust bit
(which is not used) and the BUSY bit (which is read-only), the
read-modify-write cycle can be replaced by a simple write with the IRQ FLAG
bit set to 1 and the other bits (except HOLD) set to 0.
Tested-by: Kars de Jong <jongk@linux-m68k.org>
Signed-off-by: Kars de Jong <jongk@linux-m68k.org>
Link: https://lore.kernel.org/r/20191116114620.9193-1-jongk@linux-m68k.org
Reviewed-by: Geert Uytterhoeven <geert@linux-m68k.org>
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
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