Re: [PATCH v3 1/1] power/supply/sbs-battery: Fix confusing battery status when idle or empty

[Nick Crews <ncrews@chromium.org>]

On Mon, Jul 29, 2019 at 2:07 AM Richard Tresidder
<rtresidd@electromag.com.au> wrote:
>
> When a battery or batteries in a system are in parallel then one or more
> may not be providing any current to the system.
> This fixes an incorrect status indication of FULL for the battery simply
> because it wasn't discharging at that point in time.
> The battery will now be flagged as NOT CHARGING.
> Have also added the additional check for the battery FULL DISCHARGED flag
> which will now flag a status of EMPTY.
>
> Signed-off-by: Richard Tresidder <rtresidd@electromag.com.au>
> ---
>
> Notes:
>     power/supply/sbs-battery: Fix confusing battery status when idle or empty
>
>     When a battery or batteries in a system are in parallel then one or more
>     may not be providing any current to the system.
>     This fixes an incorrect status indication of FULL for the battery simply
>     because it wasn't discharging at that point in time.
>     The battery will now be flagged as NOT CHARGING.
>     Have also added the additional check for the battery FULL DISCHARGED flag
>     which will now flag a status of EMPTY.
>
>     v2: Missed a later merge that should have been included in original patch
>     v3: Refactor the sbs_status_correct function to capture all the states for
>         normal operation rather than being spread across multile functions.
>
>  drivers/power/supply/power_supply_sysfs.c |  2 +-
>  drivers/power/supply/sbs-battery.c        | 44 +++++++++++--------------------
>  include/linux/power_supply.h              |  1 +
>  3 files changed, 18 insertions(+), 29 deletions(-)
>
> diff --git a/drivers/power/supply/power_supply_sysfs.c b/drivers/power/supply/power_supply_sysfs.c
> index f37ad4e..305e833 100644
> --- a/drivers/power/supply/power_supply_sysfs.c
> +++ b/drivers/power/supply/power_supply_sysfs.c
> @@ -51,7 +51,7 @@
>  };
>
>  static const char * const power_supply_status_text[] = {
> -       "Unknown", "Charging", "Discharging", "Not charging", "Full"
> +       "Unknown", "Charging", "Discharging", "Not charging", "Full", "Empty"
>  };
>
>  static const char * const power_supply_charge_type_text[] = {
> diff --git a/drivers/power/supply/sbs-battery.c b/drivers/power/supply/sbs-battery.c
> index 048d205..b28402d 100644
> --- a/drivers/power/supply/sbs-battery.c
> +++ b/drivers/power/supply/sbs-battery.c
> @@ -293,16 +293,18 @@ static int sbs_status_correct(struct i2c_client *client, int *intval)

sbs_status_correct() sounds like it is checking for a condition. Change
to sbs_correct_status() or sbs_correct_battery_status() to imply that it
is performing an action. Also, change "intval" to "status"?

>
>         ret = (s16)ret;
>
> -       /* Not drawing current means full (cannot be not charging) */
> -       if (ret == 0)
> -               *intval = POWER_SUPPLY_STATUS_FULL;
> -
> -       if (*intval == POWER_SUPPLY_STATUS_FULL) {
> -               /* Drawing or providing current when full */
> -               if (ret > 0)
> -                       *intval = POWER_SUPPLY_STATUS_CHARGING;
> -               else if (ret < 0)
> -                       *intval = POWER_SUPPLY_STATUS_DISCHARGING;
> +       if (ret > 0)
> +               *intval = POWER_SUPPLY_STATUS_CHARGING;
> +       else if (ret < 0)
> +               *intval = POWER_SUPPLY_STATUS_DISCHARGING;
> +       else {
> +               /* Current is 0, so how full is the battery? */
> +               if (*intval & BATTERY_FULL_CHARGED)
> +                       *intval = POWER_SUPPLY_STATUS_FULL;
> +               else if (*intval & BATTERY_FULL_DISCHARGED)
> +                       *intval = POWER_SUPPLY_STATUS_EMPTY;
> +               else
> +                       *intval = POWER_SUPPLY_STATUS_NOT_CHARGING;

This will cause some behavior changes for users. Can we get the opinion
of someone familiar with the users of this driver as to whether this is OK?

>         }
>
>         return 0;
> @@ -421,14 +423,9 @@ static int sbs_get_battery_property(struct i2c_client *client,
>                         return 0;
>                 }
>
> -               if (ret & BATTERY_FULL_CHARGED)
> -                       val->intval = POWER_SUPPLY_STATUS_FULL;
> -               else if (ret & BATTERY_DISCHARGING)
> -                       val->intval = POWER_SUPPLY_STATUS_DISCHARGING;
> -               else
> -                       val->intval = POWER_SUPPLY_STATUS_CHARGING;
> -
> -               sbs_status_correct(client, &val->intval);
> +               ret = sbs_status_correct(client, &val->intval);
> +               if (ret < 0)
> +                       return ret;
>
>                 if (chip->poll_time == 0)
>                         chip->last_state = val->intval;
> @@ -773,20 +770,11 @@ static void sbs_delayed_work(struct work_struct *work)
>
>         ret = sbs_read_word_data(chip->client, sbs_data[REG_STATUS].addr);
>         /* if the read failed, give up on this work */
> -       if (ret < 0) {
> +       if ((ret < 0) || (sbs_status_correct(chip->client, &ret) < 0)) {
>                 chip->poll_time = 0;
>                 return;
>         }
>
> -       if (ret & BATTERY_FULL_CHARGED)
> -               ret = POWER_SUPPLY_STATUS_FULL;
> -       else if (ret & BATTERY_DISCHARGING)
> -               ret = POWER_SUPPLY_STATUS_DISCHARGING;
> -       else
> -               ret = POWER_SUPPLY_STATUS_CHARGING;
> -
> -       sbs_status_correct(chip->client, &ret);
> -
>         if (chip->last_state != ret) {
>                 chip->poll_time = 0;
>                 power_supply_changed(chip->power_supply);
> diff --git a/include/linux/power_supply.h b/include/linux/power_supply.h
> index 28413f7..8fb10ec 100644
> --- a/include/linux/power_supply.h
> +++ b/include/linux/power_supply.h
> @@ -37,6 +37,7 @@ enum {
>         POWER_SUPPLY_STATUS_DISCHARGING,
>         POWER_SUPPLY_STATUS_NOT_CHARGING,
>         POWER_SUPPLY_STATUS_FULL,
> +       POWER_SUPPLY_STATUS_EMPTY,
>  };
>
>  /* What algorithm is the charger using? */
> --
> 1.8.3.1
>