Re: [PATCH 4.19 177/639] rtc: ds1307: rx8130: Fix alarm handling

From: Pavel Machek
Date: Sat Jan 25 2020 - 08:30:40 EST


Hi!

> When the EXTENSION.WADA bit is set, register 0x19 contains a bitmap of
> week days, not a day of month. As Linux only handles a single alarm
> without repetition using day of month is more flexible, so clear this
> bit. (Otherwise a value depending on time.tm_wday would have to be
> written to register 0x19.)

So the comment explains why WADA bit needs to be clear.

> @@ -749,8 +749,8 @@ static int rx8130_set_alarm(struct device *dev, struct rtc_wkalrm *t)
> if (ret < 0)
> return ret;
>
> - ctl[0] &= ~RX8130_REG_EXTENSION_WADA;
> + ctl[0] &= RX8130_REG_EXTENSION_WADA;

But then code is changed to preserve WADA bit while it was clearing it
before.

What is going on here?

Given WADA bit is already clear, is it -stable material?

Best regards,
Pavel

--
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