https://bugs.kde.org/show_bug.cgi?id=520004
Bug ID: 520004
Summary: Add support for Dell WMI Sysman firmware-attributes
battery charge limits
Classification: Applications
Product: systemsettings
Version First 6.6.4
Reported In:
Platform: Fedora RPMs
OS: Linux
Status: REPORTED
Severity: task
Priority: NOR
Component: kcm_powerdevil
Assignee: [email protected]
Reporter: [email protected]
CC: [email protected], [email protected]
Target Milestone: ---
Add support for Dell WMI Sysman battery charge thresholds in PowerDevil
Product:
Powerdevil
Component:
Battery and Power Management
---
Summary:
Modern Dell laptops expose battery charge limit controls via the Linux
`firmware-attributes` interface (`dell-wmi-sysman`), but KDE PowerDevil does
not recognize or integrate with this backend, leaving users without GUI control
of battery charge thresholds.
---
Details:
On newer Dell systems (including Dell Pro Max 16), battery charge control is
exposed via:
```
/sys/devices/virtual/firmware-attributes/dell-wmi-sysman/attributes/
PrimaryBattChargeCfg
CustomChargeStart
CustomChargeStop
```
These attributes provide full firmware-level battery charge limit control and
are already functional in the Linux kernel via the `dell-wmi-sysman` driver.
Example:
* CustomChargeStart = 50
* CustomChargeStop = 80
These values are successfully written and persisted at firmware level.
However, KDE PowerDevil does not detect or expose these controls in System
Settings → Power Management → Battery, even though:
* UPower reports battery state correctly
* kernel firmware-attributes interface is available
* Sysman provides structured metadata (min/max/default/current values)
---
Problem:
KDE PowerDevil only supports battery charge limiting via:
* ThinkPad ACPI interfaces
* Select power_supply charge_control_* sysfs entries
On Dell systems using dell-wmi-sysman, PowerDevil does not expose or utilize
the firmware-attributes interface, even though it is the primary mechanism on
modern Dell hardware.
---
Impact:
Users on newer Dell laptops cannot configure battery charge thresholds via KDE
UI and must rely on:
* manual sysfs writes
* systemd scripts
* or vendor tools
This results in inconsistent UX and fragmentation across supported hardware.
---
Expected behavior:
PowerDevil should detect and expose battery charge thresholds when available
via:
```
/sys/devices/virtual/firmware-attributes/*/attributes/*Charge*
```
specifically supporting:
* CustomChargeStart
* CustomChargeStop
* PrimaryBattChargeCfg
These should be mapped into existing PowerDevil “Battery Charge Limit” UI.
---
Suggested approach:
* Abstract firmware-attributes battery controls into a generic backend
* Add detection layer for Dell Sysman interface
* Treat Sysman as equivalent to ThinkPad ACPI charge thresholds
* Expose values through existing PowerDevil battery UI (no new UI required)
---
Workaround:
Currently users must manually write to:
```
/sys/devices/virtual/firmware-attributes/dell-wmi-sysman/attributes/
```
or create systemd services to persist settings.
---
Environment:
* KDE Plasma 6 (Fedora 44 KDE)
* Kernel: Linux (Dell WMI Sysman enabled)
* Hardware: Dell Pro Max 16 (BIOS 2.2.2)
* Power backend: UPower + PowerDevil
---
Notes:
This is not a broken feature request—Sysman is already implemented in the
kernel. This request is strictly about PowerDevil integration with an existing
upstream interface.
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