Re: [PATCH] rtc: rs5c372: Fix reading from rtc when the oscillator got interrupted.

From: Alexandre Belloni
Date: Wed Feb 06 2019 - 04:58:17 EST

On 06/02/2019 06:33:39+0000, Oliver.Rohe@xxxxxxxx wrote:
> >> + switch (rs5c->type) {
> >> + case rtc_r2025sd:
> >> + case rtc_r2221tl:
> >> + if (ctrl2 & R2x2x_CTRL2_VDET)
> >> + dev_warn(&client->dev, "rtc battery voltage drop below threshold detected.\n");
> >
> > VDET doesn't mean anything specific regarding timekeeping so I wouldn't warn here.
> VDET means in case the chip is powered by a battery, that is about to die sometime soon, it gives you heads up.

Yes but my statement stands true, this doesn't have any direct
implication regarding timekeeping.

There is the RTC_VL_READ ioctl to check voltage low. It is not weel
designed but this is what we have now.

> >
> >> + if (ctrl2 & R2x2x_CTRL2_PON)
> >> + dev_warn(&client->dev, "rtc battery voltage drop to zero detected.\n");
> >
> > You should return -EINVAL directly here
> The PON implies the XSTP bit, so I only return from there, just to print all the warning messages, but I can return directly from here if you want.

As you said, PON implies XSTP so I'm not sure it is valuable to have both

Alexandre Belloni, Bootlin
Embedded Linux and Kernel engineering