Dell precision 5510 providing incorrect power state to linux

Hello Project Sputnik,

I just recently purchased a dell precision 5510 with ubuntu 14.04 installed on it, and began my usual setup of a laptop, including installing TLP. It was at this point that I realized that TLP did not recognize the power state of my laptop (on battery vs on AC) and began to investigate.

I did some digging and found that the battery state as provided via udev does not contain the correct power state of the machine.
A paste of running sudo tlp --pev which prints udev state for the power system, with some of my own notes added in (( between these))

--- TLP 0.9 --------------------------------------------

+++ Monitor power supply events -- cancel with ^C

monitor will print the received events for:
UDEV - the event which udev sends out after rule processing

((I unplugged the power supply here))

UDEV [2193.174519] change /devices/LNXSYSTM:00/LNXSYBUS:00/PNP0C0A:00/power_supply/BAT0 (power_supply)
ACTION=change
DEVPATH=/devices/LNXSYSTM:00/LNXSYBUS:00/PNP0C0A:00/power_supply/BAT0
POWER_SUPPLY_CAPACITY=101
POWER_SUPPLY_CAPACITY_LEVEL=Normal
POWER_SUPPLY_CHARGE_FULL=7268000
POWER_SUPPLY_CHARGE_FULL_DESIGN=7368000
POWER_SUPPLY_CHARGE_NOW=7368000
POWER_SUPPLY_CURRENT_NOW=1000
POWER_SUPPLY_CYCLE_COUNT=0
POWER_SUPPLY_MANUFACTURER=LGC-LGC3.67
POWER_SUPPLY_MODEL_NAME=DELL T453X6C
POWER_SUPPLY_NAME=BAT0
POWER_SUPPLY_PRESENT=1
POWER_SUPPLY_SERIAL_NUMBER=45263
POWER_SUPPLY_STATUS=Discharging
POWER_SUPPLY_TECHNOLOGY=Li-ion
POWER_SUPPLY_VOLTAGE_MIN_DESIGN=11400000
POWER_SUPPLY_VOLTAGE_NOW=13079000
SEQNUM=3866
SUBSYSTEM=power_supply
USEC_INITIALIZED=2193080406

((I plugged in the power supply here))

UDEV [2195.612852] change /devices/LNXSYSTM:00/LNXSYBUS:00/PNP0C0A:00/power_supply/BAT0 (power_supply)
ACTION=change
DEVPATH=/devices/LNXSYSTM:00/LNXSYBUS:00/PNP0C0A:00/power_supply/BAT0
POWER_SUPPLY_CAPACITY=101
POWER_SUPPLY_CAPACITY_LEVEL=Full
POWER_SUPPLY_CHARGE_FULL=7268000
POWER_SUPPLY_CHARGE_FULL_DESIGN=7368000
POWER_SUPPLY_CHARGE_NOW=7368000
POWER_SUPPLY_CYCLE_COUNT=0
POWER_SUPPLY_MANUFACTURER=LGC-LGC3.67
POWER_SUPPLY_MODEL_NAME=DELL T453X6C
POWER_SUPPLY_NAME=BAT0
POWER_SUPPLY_PRESENT=1
POWER_SUPPLY_SERIAL_NUMBER=45263
POWER_SUPPLY_STATUS=Full
POWER_SUPPLY_TECHNOLOGY=Li-ion
POWER_SUPPLY_VOLTAGE_MIN_DESIGN=11400000
POWER_SUPPLY_VOLTAGE_NOW=13060000
SEQNUM=3867
SUBSYSTEM=power_supply
USEC_INITIALIZED=2195572552

Notice that the power supply is always BAT0 and that the only way to tell the current state of the system is to guess based upon the POWER_SUPPLY_STATUS

After seeing this I also took a look  at /sys/class/power_supply/ and found that only BAT0 exists even though the AC adapter is plugged in.

Finally I have found other users who are experiencing this problem https://github.com/linrunner/TLP/issues/223

based upon what I can find, this issue comes down to a bios problem with the laptop, and it not providing the correct power state back to the linux kernel.

I am very much interested in helping find a solution to this problem, as I would rather not have to setup strange udev rules around POWER_SUPPLY_STATUS to help save battery on my machine :emotion-4:

Please let me know if there is anything I can do to help

Mark