Re: [PATCH v3 3/5] power: supply: max17040: Config alert SOC low level threshold from FDT

[Matheus Castello]

On 5/29/19 11:46 AM, Krzysztof Kozlowski wrote:
> On Mon, 27 May 2019 at 04:46, Matheus Castello <matheus@xxxxxxxxxxxxxxx> wrote:
> > For configuration of fuel gauge alert for a low level state of charge
> > interrupt we add a function to config level threshold and a device tree
> > binding property to set it in flatned device tree node.
> >
> > Now we can use "maxim,alert-low-soc-level" property with the values from
> > 1% up to 32% to configure alert interrupt threshold.
> >
> > Signed-off-by: Matheus Castello <matheus@xxxxxxxxxxxxxxx>
> > ---
> >   drivers/power/supply/max17040_battery.c | 52 +++++++++++++++++++++++--
> >   1 file changed, 49 insertions(+), 3 deletions(-)
> >
> > diff --git a/drivers/power/supply/max17040_battery.c b/drivers/power/supply/max17040_battery.c
> > index b7433e9ca7c2..2f4851608cfe 100644
> > --- a/drivers/power/supply/max17040_battery.c
> > +++ b/drivers/power/supply/max17040_battery.c
> > @@ -29,6 +29,9 @@
> >   #define MAX17040_DELAY         1000
> >   #define MAX17040_BATTERY_FULL  95
> >
> > +#define MAX17040_ATHD_MASK             0xFFC0
> > +#define MAX17040_ATHD_DEFAULT_POWER_UP 4
> > +
> >   struct max17040_chip {
> >          struct i2c_client               *client;
> >          struct delayed_work             work;
> > @@ -43,6 +46,8 @@ struct max17040_chip {
> >          int soc;
> >          /* State Of Charge */
> >          int status;
> > +       /* Low alert threshold from 32% to 1% of the State of Charge */
> > +       u32 low_soc_alert_threshold;
> >   };
> >
> >   static int max17040_get_property(struct power_supply *psy,
> > @@ -99,6 +104,28 @@ static void max17040_reset(struct i2c_client *client)
> >          max17040_write_reg(client, MAX17040_CMD, 0x0054);
> >   }
> >
> > +static int max17040_set_low_soc_threshold_alert(struct i2c_client *client,
> > +       u32 level)
> > +{
> > +       int ret;
> > +       u16 data;
> > +
> > +       /* check if level is between 1% and 32% */
> > +       if (level > 0 && level < 33) {
> > +               level = 32 - level;
> > +               data = max17040_read_reg(client, MAX17040_RCOMP);
> > +               /* clear the alrt bit and set LSb 5 bits */
> > +               data &= MAX17040_ATHD_MASK;
> > +               data |= level;
> > +               max17040_write_reg(client, MAX17040_RCOMP, data);
> > +               ret = 0;

I will put the return of max17040_write_reg on ret, instead of ret = 0.

> > +       } else {
> > +               ret = -EINVAL;
> > +       }
>
> This is unusual way of handling error... when you parse DTS, you
> accept any value for "level" (even incorrect one). You validate the
> value later when setting it and show an error... however you ignore
> the error of max17040_write_reg() here... This is correct but looks
> unusual.

Ok, so would it be better to check the level value in 
"max17040_get_of_data" and return an error there if the input is wrong?

Best Regards,
Matheus Castello

> Best regards,
> Krzysztof