ACPI issues / brightness on ASUS Laptop (K50IJ) -- Fix Available

[Paolo Ornati]

Binary package hint: linux-image-2.6.32-24-generic

On this laptop (ASUS K50IJ), with 2.6.32 based kernels I get these ACPI errors in dmesg:

[ 19.590966] ACPI Exception: AE_AML_BUFFER_LIMIT, Index (000000064) is beyond end of object (20090903/exoparg2-445)
[ 19.590975] ACPI Error (psparse-0537): Method parse/execution failed [\_SB_.PCI0.SBRG.EC0_.STBR] (Node ffff88013ba43180), AE_AML_BUFFER_LIMIT
[ 19.591015] ACPI Error (psparse-0537): Method parse/execution failed [\_SB_.PCI0.VGA_.LCDD._BCM] (Node ffff88013ba3d400), AE_AML_BUFFER_LIMIT
[ 19.591057] ACPI Error: Evaluating _BCM failed (20090903/video-528)

Changing brightness doesn't work.

This was fixed in vanilla kernel between 2.6.32 and 2.6.33 by this commit:

-------------------------------------------------------------------------------------------
commit 81074e90f5c150ca70ab8dfcc77860cbe76f364d
Author: Zhang Rui <email address hidden>
Date: Mon Dec 21 16:13:15 2009 +0800

    ACPI: disable _OSI(Windows 2009) on Asus K50IJ

    Fix a win7 compability issue on Asus K50IJ.

    Here is the _BCM method of this laptop:
                        Method (_BCM, 1, NotSerialized)
                        {
                            If (LGreaterEqual (OSFG, OSVT))
                            {
                                If (LNotEqual (OSFG, OSW7))
                                {
                                    Store (One, BCMD)
                                    Store (GCBL (Arg0), Local0)
                                    Subtract (0x0F, Local0, LBTN)
                                    ^^^SBRG.EC0.STBR ()
                                    ...
                                }
                                Else
                                {
                                    DBGR (0x0B, Zero, Zero, Arg0)
                                    Store (Arg0, LBTN)
                                    ^^^SBRG.EC0.STBR ()
                                    ...
                                }
                            }
                        }
    LBTN is used to store the index of the brightness level in the _BCL.
    GCBL is a method that convert the percentage value to the index value.
    If _OSI(Windows 2009) is not disabled, LBTN is stored a percentage
    value which is surely beyond the end of _BCL package.

    http://bugzilla.kernel.org/show_bug.cgi?id=14753
------------------------------------------------------------------------------------

Please add this workaround to Ubuntu Lucid kernel.

Debian Squeeze kernel needs this too.

[Leann Ogasawara (leannogasawara)]

This patch is included in the latest Maverick 2.6.35 based kernel. I'm therefore marking this Fix Released for Maverick. I'll open a Lucid nomination and leave it to the discretion of the Ubuntu kernel SRU team to backport to Lucid. Thanks.

[Paolo Ornati (ornati)]

I reported it upstream now (<email address hidden>), so maybe it will be included in 2.6.32.y and flow to distros from there...

[Paolo Ornati (ornati)]

The patch is now part of v2.6.32.23.

[Julian Wiedmann (jwiedmann)]

Paolo:
The patch landed in Lucid a long time ago, can you confirm that this is fixed?

[Paolo Ornati (ornati)]

I changed laptop in the meanwhile... I don't have the old one any more.

If the patch is included I think it can be closed.