Re: [PATCH] power: supply: max17042_battery: infer the status when no supplier is described

[Hans de Goede]

Hi,

On 19-Oct-26 4:33 PM, Derek Ross wrote:
> When no power supply is described as supplying the battery,
> power_supply_am_i_supplied() returns -ENODEV and the driver reports
> POWER_SUPPLY_STATUS_UNKNOWN, even though the gauge measures the battery
> current itself.
> 
> That is the case on the Pixel 7 Pro, where the charger is left running
> by the bootloader and no charger driver is bound yet. The battery read
> "Unknown" while taking in 1.2 A, so the desktop showed no charging
> indicator and upower treated the phone as discharging: at its critical
> percentage it put a charging phone to sleep.
> 
> When no supplier is described and current sense is enabled, take the
> status from the measured current: charging while current flows into the
> battery, full when the gauge reports end of charge and no current flows,
> discharging otherwise. A described supplier keeps the existing logic, and
> without current sense the status stays unknown.
> 
> Signed-off-by: Derek Ross <derekross@xxxxxxxxx>

Thanks, patch looks good to me:

Reviewed-by: Hans de Goede <johannes.goede@xxxxxxxxxxxxxxxx>

Regards,

Hans



> ---
>  drivers/power/supply/max17042_battery.c | 21 ++++++++++++++++-----
>  1 file changed, 16 insertions(+), 5 deletions(-)
> 
> diff --git a/drivers/power/supply/max17042_battery.c b/drivers/power/supply/max17042_battery.c
> index 8138b52e05e1..c437d80700a6 100644
> --- a/drivers/power/supply/max17042_battery.c
> +++ b/drivers/power/supply/max17042_battery.c
> @@ -148,18 +148,26 @@ static int max17042_get_status(struct max17042_chip *chip, int *status)
>  {
>  	int ret, charge_full, charge_now;
>  	int current_now;
> +	bool supplied, full;
>  	u32 data;
>  
>  	ret = power_supply_am_i_supplied(chip->battery);
> -	if (ret < 0) {
> -		*status = POWER_SUPPLY_STATUS_UNKNOWN;
> -		return 0;
> -	}
>  	if (ret == 0) {
>  		*status = POWER_SUPPLY_STATUS_DISCHARGING;
>  		return 0;
>  	}
>  
> +	/*
> +	 * A negative value means no supplier is described, e.g. a charger the
> +	 * bootloader left running that no driver owns. The gauge's own current
> +	 * sense still tells which way charge flows, so use it when it's there.
> +	 */
> +	supplied = ret > 0;
> +	if (!supplied && !chip->enable_current_sense) {
> +		*status = POWER_SUPPLY_STATUS_UNKNOWN;
> +		return 0;
> +	}
> +
>  	/*
>  	 * The MAX170xx has builtin end-of-charge detection and will update
>  	 * FullCAP to match RepCap when it detects end of charging.
> @@ -178,7 +186,8 @@ static int max17042_get_status(struct max17042_chip *chip, int *status)
>  	if (ret < 0)
>  		return ret;
>  
> -	if ((charge_full - charge_now) <= MAX17042_FULL_THRESHOLD) {
> +	full = (charge_full - charge_now) <= MAX17042_FULL_THRESHOLD;
> +	if (supplied && full) {
>  		*status = POWER_SUPPLY_STATUS_FULL;
>  		return 0;
>  	}
> @@ -200,6 +209,8 @@ static int max17042_get_status(struct max17042_chip *chip, int *status)
>  
>  	if (current_now > 0)
>  		*status = POWER_SUPPLY_STATUS_CHARGING;
> +	else if (full && current_now == 0)
> +		*status = POWER_SUPPLY_STATUS_FULL;
>  	else
>  		*status = POWER_SUPPLY_STATUS_DISCHARGING;
>