This is a note to let you know that I've just added the patch titled rtc: m41t80: fix SQW dividers override when setting a date to the 4.9-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary The filename of the patch is: rtc-m41t80-fix-sqw-dividers-override-when-setting-a-date.patch and it can be found in the queue-4.9 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let <stable@xxxxxxxxxxxxxxx> know about it. >From foo@baz Mon Apr 9 17:09:24 CEST 2018 From: Gary Bisson <gary.bisson@xxxxxxxxxxxxxxxxxxx> Date: Tue, 25 Apr 2017 16:45:15 +0200 Subject: rtc: m41t80: fix SQW dividers override when setting a date From: Gary Bisson <gary.bisson@xxxxxxxxxxxxxxxxxxx> [ Upstream commit 0f546b058b86ea2f661cc7a6e931cee5a29959ef ] This patch is only relevant for RTC with the SQ_ALT feature which means the clock output frequency divider is stored in the weekday register. Current implementation discards the previous dividers value and clear them as soon as the time is set. Signed-off-by: Gary Bisson <gary.bisson@xxxxxxxxxxxxxxxxxxx> Signed-off-by: Alexandre Belloni <alexandre.belloni@xxxxxxxxxxxxxxxxxx> Signed-off-by: Sasha Levin <alexander.levin@xxxxxxxxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- drivers/rtc/rtc-m41t80.c | 12 ++++++++++++ 1 file changed, 12 insertions(+) --- a/drivers/rtc/rtc-m41t80.c +++ b/drivers/rtc/rtc-m41t80.c @@ -168,6 +168,7 @@ static int m41t80_get_datetime(struct i2 /* Sets the given date and time to the real time clock. */ static int m41t80_set_datetime(struct i2c_client *client, struct rtc_time *tm) { + struct m41t80_data *clientdata = i2c_get_clientdata(client); unsigned char buf[8]; int err, flags; @@ -183,6 +184,17 @@ static int m41t80_set_datetime(struct i2 buf[M41T80_REG_YEAR] = bin2bcd(tm->tm_year - 100); buf[M41T80_REG_WDAY] = tm->tm_wday; + /* If the square wave output is controlled in the weekday register */ + if (clientdata->features & M41T80_FEATURE_SQ_ALT) { + int val; + + val = i2c_smbus_read_byte_data(client, M41T80_REG_WDAY); + if (val < 0) + return val; + + buf[M41T80_REG_WDAY] |= (val & 0xf0); + } + err = i2c_smbus_write_i2c_block_data(client, M41T80_REG_SSEC, sizeof(buf), buf); if (err < 0) { Patches currently in stable-queue which might be from gary.bisson@xxxxxxxxxxxxxxxxxxx are queue-4.9/rtc-m41t80-fix-sqw-dividers-override-when-setting-a-date.patch