On 12/06/2023 14:30:18+0200, Rasmus Villemoes wrote:
> On 12/06/2023 13.30, Rasmus Villemoes wrote:
>
> > diff --git a/drivers/rtc/rtc-isl12022.c b/drivers/rtc/rtc-isl12022.c
> > index 1b6659a9b33a..690dbb446d1a 100644
> > --- a/drivers/rtc/rtc-isl12022.c
> > +++ b/drivers/rtc/rtc-isl12022.c
> > @@ -280,8 +280,25 @@ static void isl12022_set_trip_levels(struct device *dev)
> > mask = ISL12022_REG_VB85_MASK | ISL12022_REG_VB75_MASK;
> >
> > ret = regmap_update_bits(regmap, ISL12022_REG_PWR_VBAT, mask, val);
> > - if (ret)
> > + if (ret) {
> > dev_warn(dev, "unable to set battery alarm levels: %d\n", ret);
> > + return;
> > + }
> > +
> > + ret = regmap_write_bits(regmap, ISL12022_REG_BETA,
> > + ISL12022_BETA_TSE, ISL12022_BETA_TSE);
> > + if (ret) {
> > + dev_warn(dev, "unable to trigger battery level detection: %d\n", ret);
> > + return;
> > + }
> > +
> > + ret = isl12022_read_sr(regmap);
>
> So testing this a bit more thoroughly reveals that the LBAT85/LBAT75
> bits do not get updated immediately after the TSE bit is set; one needs
> to wait a little before the battery voltage detection is done and the SR
> bits updated. Unfortunately, the data sheet doesn't say anything about
> how long that might be or if there's some busy bit one could look at;
> all it says is actually exactly what I've done above:
>
> The battery level monitor is not functional in battery backup
> mode. In order to read the monitor bits after powering up VDD,
> instigate a battery level measurement by setting the TSE bit to
> "1" (BETA register), and then read the bits.
>
> IOW, please don't apply this patch until I figure out how to do this
> properly.
>
The datasheet states 22ms for the temperature conversion so I would
expect it takes about that time.
--
Alexandre Belloni, co-owner and COO, Bootlin
Embedded Linux and Kernel engineering
https://bootlin.com
