The handling of PMIC register reads through writing 0 to address 4
of the OpRegion is wrong. Instead of returning the read value
through the value64, which is a no-op for function == ACPI_WRITE calls,
store the value and then on a subsequent function == ACPI_READ with
address == 3 (the address for the value field of the OpRegion)
return the stored value.
This has been tested on a Xiaomi Mi Pad 2 and makes the ACPI battery dev
there mostly functional (unfortunately there are still other issues).
Here are the SET() / GET() functions of the PMIC ACPI device,
which use this OpRegion, which clearly show the new behavior to
be correct:
OperationRegion (REGS, 0x8F, Zero, 0x50)
Field (REGS, ByteAcc, NoLock, Preserve)
{
CLNT, 8,
SA, 8,
OFF, 8,
VAL, 8,
RWM, 8
}
Method (GET, 3, Serialized)
{
If ((AVBE == One))
{
CLNT = Arg0
SA = Arg1
OFF = Arg2
RWM = Zero
If ((AVBG == One))
{
GPRW = Zero
}
}
Return (VAL) /* \_SB_.PCI0.I2C7.PMI5.VAL_ */
}
Method (SET, 4, Serialized)
{
If ((AVBE == One))
{
CLNT = Arg0
SA = Arg1
OFF = Arg2
VAL = Arg3
RWM = One
If ((AVBG == One))
{
GPRW = One
}
}
}
Fixes: 0afa877a56 ("ACPI / PMIC: intel: add REGS operation region support")
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
009a789443