Thanks Earl,
When you run the command:
cat /proc/acpi/battery/BAT0/state
present: yes
capacity state: ok
charging state: charged
present rate: 0 mA
remaining capacity: 4406 mAh
present voltage: 12527 mV
the ACPI driver evaluates the ACPI method _BST. The
/proc/acpi/battery/BAT0/state fields are mapped as follows:
charging state: -- _BST package element 0
values: 0 = charged, 1 = discharging, 2 = charging, 4 = critical
present rate:-- _BST package element 1
remaining capacity: -- _BST package element 2
present voltage: -- _BST package element 3
The extracted _BST method from the DSDT in the acpidump is as follows (I
added the comments)
// Defaulted _BST return package
Name (PKG2, Package (0x04)
{
Zero,
One,
One,
0x39D0
})
Method (_BST, 0, NotSerialized)
{
If (ECON)
{
Sleep (0x30)
Store (^^PCI0.LPCB.EC0.BST0, Local0)
And (Local0, 0x07, Local0)
// read battery charging state from embedded controller memory
Sleep (0x30)
Store (^^PCI0.LPCB.EC0.BRC0, Local1) // read
remaining capacity from embedded controller memory
Sleep (0x30)
Store (^^PCI0.LPCB.EC0.BPV0, Local2) // read
present voltage from embedded controller memory
Store (Local0, Index (PKG2, Zero)) //
set charging state
Store (Zero, Index (PKG2, One)) //
set present rate = 0
Store (Local1, Index (PKG2, 0x02)) //
set remaining capacity
Store (Local2, Index (PKG2, 0x03)) //
set present voltage
}
Return (PKG2)// return the battery status
package to the Operating System that evaluated _BST
}
So, as one can see, the present rate field is being set to zero in the
firmware, and the kernel is just reporting exactly what the firmware is
returning.
Section 10.2.2.6 of version 4.0a of the ACPI specification states:
Batteries that are rechargeable and are in the discharging state are required
to
return a valid Battery Present Rate value.
So in my opinion this should be reported as a bug to the BIOS vendor.
The_BST method as it is not conforming to the ACPI specification,
section 10.2.2.6, Battery Present Rate value.
There is little we can do in software to fix this at the kernel level.
** Tags added: acpi-battery
** Changed in: gnome-power-manager (Ubuntu)
Assignee: (unassigned) = Colin King (colin-king)
** Changed in: gnome-power-manager (Ubuntu)
Importance: Undecided = Medium
** Changed in: gnome-power-manager (Ubuntu)
Status: New = Triaged
** Summary changed:
- Battery rate always 0
+ Battery present rate always 0 from /proc/acpi/battery/BAT?/state
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You received this bug notification because you are a member of Ubuntu
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https://bugs.launchpad.net/bugs/728623
Title:
Battery present rate always 0 from /proc/acpi/battery/BAT?/state
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