Re: [PATCH] rtc: rv3028: Improve trickle charger logic

[Andrej Picej]

On 8. 06. 23 12:35, Andrej Picej wrote:
> Hi Alexandre,
>
> On 8. 06. 23 11:31, Alexandre Belloni wrote:
> > Hello,
> >
> > On 08/06/2023 11:04:46+0200, Andrej Picej wrote:
> > > +    ret = regmap_read(rv3028->regmap, RV3028_BACKUP, &val_old);
> > > +    if (ret < 0)
> > > +        return ret;
> > > +
> > > +    /* mask out only trickle charger bits */
> > > +    val_old = val_old & (RV3028_BACKUP_TCE | RV3028_BACKUP_TCR_MASK);
> > > +
> > >       /* setup trickle charger */
> > > -    if (!device_property_read_u32(&client->dev, 
> > > "trickle-resistor-ohms",
> > > -                      &ohms)) {
> > > +    if (device_property_read_u32(&client->dev, 
> > > "trickle-resistor-ohms", &ohms)) {
> > > +        /* disable the trickle charger */
> > > +        val = 0;
> >
> > You can't do that, this will break existing users that may set the
> > trickle charger from their bootloader for example.
>
> hmm...ok I understand that idea. I thought that might be a problem. I 
> guess keeping default as it is has a higher priority.
>
> What do you say if setting this property to 0 (or maybe -1) disabled the 
> trickle charger?
> So if users add:
>
> trickle-resistor-ohms = <0>;
> or
> trickle-resistor-ohms = <(-1)>;
>
> this would mean disable the trickle charger?
>
> I know it is far from optimal, but this would solve both things:
> * not braking existing implementation,
> * users could disable the trickle charger.
>
> What do you say.

Gentle ping. Would this be something you would consider?

Thanks,
Andrej

> Thanks for your review.
>
> Best regards,
> Andrej
>
> > > +    } else {
> > >           int i;
> > >           for (i = 0; i < ARRAY_SIZE(rv3028_trickle_resistors); i++)
> > > @@ -947,15 +957,21 @@ static int rv3028_probe(struct i2c_client *client)
> > >                   break;
> > >           if (i < ARRAY_SIZE(rv3028_trickle_resistors)) {
> > > -            ret = rv3028_update_cfg(rv3028, RV3028_BACKUP, 
> > > RV3028_BACKUP_TCE |
> > > -                         RV3028_BACKUP_TCR_MASK, RV3028_BACKUP_TCE | 
> > > i);
> > > -            if (ret)
> > > -                return ret;
> > > +            /* enable the trickle charger and setup its resistor 
> > > accordingly */
> > > +            val = RV3028_BACKUP_TCE | i;
> > >           } else {
> > >               dev_warn(&client->dev, "invalid trickle resistor 
> > > value\n");
> > >           }
> > >       }
> > > +    /* only update EEPROM if changes are necessary */
> > > +    if (val_old != val) {
> > > +        ret = rv3028_update_cfg(rv3028, RV3028_BACKUP, 
> > > RV3028_BACKUP_TCE |
> > > +                    RV3028_BACKUP_TCR_MASK, val);
> > > +        if (ret)
> > > +            return ret;
> > > +    }
> > > +
> > >       ret = rtc_add_group(rv3028->rtc, &rv3028_attr_group);
> > >       if (ret)
> > >           return ret;
> > > --
> > > 2.25.1