linux-kernel - [Question] rtc wake behavior and sysfs

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Message-ID: <CAMdYzYrYdDYF_Y_TwQ65u=Ymu2_8Rs9KWm_TfXcaPGTwucT=jg@mail.gmail.com>
Date:   Mon, 5 Oct 2020 09:13:08 -0400
From:   Peter Geis <pgwipeout@...il.com>
To:     a.zummo@...ertech.it, alexandre.belloni@...tlin.com,
        "Rafael J. Wysocki" <rjw@...ysocki.net>, len.brown@...el.com,
        pavel@....cz, Greg KH <gregkh@...uxfoundation.org>
Cc:     linux-rtc@...r.kernel.org, linux-pm@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-tegra@...r.kernel.org
Subject: [Question] rtc wake behavior and sysfs

Good Morning,

While testing suspend to ram on the Ouya, I encountered an interesting
issue with the rtc-tps65910 driver.
Attempting to use rtc-wake on the default configuration returned:
rtcwake: /dev/rtc0 not enabled for wakeup events
This is due to:
eb5eba4ef722 drivers/rtc/rtc-tps65910.c: enable/disable wake in suspend/resume
This commit changed this driver's behavior to not enable wakeup by
default, but enables it when entering sleep mode.
This seems to be odd behavior to me.
Looking at a few other rtc drivers show they simply enable themselves
as wakeup sources by default.

I also found the sysfs entries are at /sys/devices/ ..
/tps65910-rtc/power but are missing at /sys/class/rtc/rtc0/power/

I have two questions.
 - Should the sysfs wakeup entries be missing at /sys/class/rtc/rtc0/power/ ?
 - Shouldn't a rtc be enabled as a wakeup source by default?

Thank you for your time.

Very Respectfully,
Peter Geis