Re: [PATCH 1/2] power: supply: qcom_battmgr: fix CHARGE_FULL* on SM8350-class firmware

[Konrad Dybcio <konrad.dybcio@oss.qualcomm.com>]

On 8/29/26 7:45 AM, Jan-Michael Brummer wrote:
> battmgr->unit is only ever assigned in the BATTMGR_BAT_INFO handler of
> the SC8280XP callback. The SM8350-class firmware does not implement that
> request - every property is fetched individually via
> BATTMGR_BAT_PROPERTY_GET - so unit keeps its zero-initialised value,
> QCOM_BATTMGR_UNIT_mWh.
> 
> POWER_SUPPLY_PROP_CHARGE_FULL and POWER_SUPPLY_PROP_CHARGE_FULL_DESIGN
> are guarded by 'if (unit != QCOM_BATTMGR_UNIT_mAh) return -ENODATA;',
> hence both properties always fail on these platforms, even though the
> values are requested from the firmware and stored in
> info.last_full_capacity and info.design_capacity on every access:
> 
>   $ cat /sys/class/power_supply/qcom-battmgr-bat/charge_full
>   cat: read error: No data available
> 
> Without a full charge value userspace cannot derive an absolute energy
> level, so UPower reports a zero energy level and never computes a
> time-to-empty/time-to-full estimate:
> 
>     energy:              0 Wh
>     energy-full:         0 Wh
>     energy-rate:         12.4713 W
>     percentage:          59%
> 
> The firmware of this class reports charge domain values, so set the unit
> statically when registering the SM8350/SM8550 power supplies. With this
> patch the properties read back consistently on a Fairphone 5:
> 
>   charge_full         4116000
>   charge_full_design  4260000
>   capacity            85
> 
> Fixes: 29e8142b5623 ("power: supply: Introduce Qualcomm PMIC GLINK power supply")
> Signed-off-by: Jan-Michael Brummer <jan.brummer@tabos.org>
> ---

This also implicitly unlocks reporting

POWER_SUPPLY_PROP_CHARGE_EMPTY
POWER_SUPPLY_PROP_CHARGE_NOW

which are not populated and will always report 0.

We should probably further limit that.

Konrad