linux-kernel - Re: [PATCH v1 RFC] rtc: meson-vrtc: Use ktime_get_real

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Date:   Tue, 21 Mar 2023 02:52:31 -0700
From:   Kevin Hilman <khilman@...libre.com>
To:     Martin Blumenstingl <martin.blumenstingl@...glemail.com>,
        linux-rtc@...r.kernel.org, linux-amlogic@...ts.infradead.org
Cc:     Alessandro Zummo <a.zummo@...ertech.it>,
        Alexandre Belloni <alexandre.belloni@...tlin.com>,
        Neil Armstrong <neil.armstrong@...aro.org>,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
        Martin Blumenstingl <martin.blumenstingl@...glemail.com>
Subject: Re: [PATCH v1 RFC] rtc: meson-vrtc: Use ktime_get_real_ts64() to
 get the current time

Martin Blumenstingl <martin.blumenstingl@...glemail.com> writes:

> The VRTC alarm register can be programmed with an amount of seconds
> after which the SoC will be woken up by the VRTC timer again. We are
> already converting the alarm time from meson_vrtc_set_alarm() to
> "seconds since 1970". This means we also need to use "seconds since
> 1970" for the current time.
>
> This fixes a problem where setting the alarm to one minute in the future
> results in the firmware (which handles wakeup) to output (on the serial
> console) that the system will be woken up in billions of seconds.
> ktime_get_raw_ts64() returns the time since boot, not since 1970. Switch
> to ktime_get_real_ts64() to fix the calculation of the alarm time and to
> make the SoC wake up at the specified date/time. Also the firmware
> (which manages suspend) now prints either 59 or 60 seconds until wakeup
> (depending on how long it takes for the system to enter suspend).
>
> Fixes: 6ef35398e827 ("rtc: Add Amlogic Virtual Wake RTC")
> Signed-off-by: Martin Blumenstingl <martin.blumenstingl@...glemail.com>

Reviewed-by: Kevin Hilman <khilman@...libre.com>