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Fixing incorrect lid state

Ting Wai

• 3 min read

When I install a Linux distro to my VAIO notebook, I found that there is an annoying bug with the lid switch. It does not get updated whenever I suspend on lid close, it means cat /proc/acpi/button/lid/LID/state will output state: close. When I close the lid again, it won't suspend, instead, it will change the state to open. So in order for it to suspend again on lid close after the first suspend, I have to close it, reopen the lid and close it again.

I have tried installing Linux Mint, Fedora, Fuduntu and Xubuntu, but it is not fixed in any of the distros. So, I don't think it is distro problems. While researching this issues (which I spent two full days), I found that Linux got an amazing feature that enable users to dynamically loading DSDT at boot time, there is no need to update the BIOS. So here's the instuctions:

1. Install iasl using yum, apt-get or whatever package management you are using.

2. Extract DSDT:

$ sudo cat /sys/firmware/acpi/tables/DSDT > dsdt.aml

3. Disassemble dsdt.aml using the following command, this should create a new file dsdt.dsl:

$ iasl -d dsdt.aml

4. Compile it using:

$ iasl -tc dsdt.dsl

5. Fix any compiler errors, warnings and remarks. On my machine, the output is:

dsdt.dsl  1352:                         And (CTRL, 0x1E)
Warning  1106 -                                 ^ Result is not used, operator has no effect

dsdt.dsl  1584:                     0x00000000,         // Length
Error    4122 -                              ^ Invalid combination of Length and Min/Max fixed flags

dsdt.dsl  2443:                                 Name (_T_0, 0x00)
Remark   5111 -            Use of compiler reserved name ^  (_T_0)

dsdt.dsl  2521:                                 Name (_T_0, 0x00)
Remark   5111 -            Use of compiler reserved name ^  (_T_0)

a. The first one is on line 1352 can be fixed simply by changing And (CTRL, 0x1E) to And (CTRL, 0x1E, CTRL).

b. The second one is on line 1584, the length should be Range Maximum - Range Minimum + 1, on my machine, so fire up a hex calculator and start subtracting. On my machine, it's 0xE0000000 (0xDFFFFFFF - 0x00000000 + 0x00000001).

c. The third and fourth line is on line 2443 and 2521, because it uses a reserved name, simply replacing all instances of _T_0 to T_0 will stop the complaints. In vim, it is as simple as issuing :%s/_T_0/T_0/g in command mode.

6. Once everything is fixed (no errors, warning or remarks), add the following line to _WAK method, simply search for _WAK in dsdt.dsl:

If (LNotEqual (0x00, LIDS))
    {
        Store (0x00, LIDS)
        Notify (\_SB.LID, 0x80)
    }

NOTE 1: You might need to change \_SB.LID to match your path to LID method or on some machine LID0. Method name is preceded by an _ (underscore), so you can search for _LID in dsdt.dsl. After you found it, you have to determine the scope, scroll up until you found Scope keyword that your LID or LID0 method belongs to, inside the bracket is the scope name. It may be in more than one scope, so, it might be \_PCI0.SB.LID. If you specify an incorrect path to LID method, you will receive the following error:

dsdt.dsl   300:             Notify (LID, 0x80)
Error    4068 -                       ^ Object is not accessible from this scope (LID_)

NOTE 2: What this function does is just to update the lid state once it is resumed from sleep. According to the ACPICA documentation, _WAK method is called by AcpiLeaveSleepState() function of ACPI. If the lid is open, the LIDS variable is 0x00, or 0x01 otherwise. So these few lines translate to "if lid state is not open (closed), change lid state to open and call LID method".

7. Compile it using iasl -tc dsdt.dsl.

8. If no errors, warnings or remarks, add the following lines to /etc/grub.d/01_acpi:

# Uncomment to load custom ACPI table
GRUB_CUSTOM_ACPI="/boot/dsdt.aml"


# DON'T MODIFY ANYTHING BELOW THIS LINE!


prefix=/usr
exec_prefix=${prefix}
libdir=${exec_prefix}/lib


. /usr/share/grub/grub-mkconfig_lib
#. ${libdir}/grub/grub-mkconfig_lib


# Load custom ACPI table
if [ x${GRUB_CUSTOM_ACPI} != x ] && [ -f ${GRUB_CUSTOM_ACPI} ] \
	&& is_path_readable_by_grub ${GRUB_CUSTOM_ACPI}; then
    echo "Found custom ACPI table: ${GRUB_CUSTOM_ACPI}" >&2
    prepare_grub_to_access_device `${grub_probe} --target=device ${GRUB_CUSTOM_ACPI}` | sed -e "s/^/  /"
    cat << EOF
acpi (\$root)`make_system_path_relative_to_its_root ${GRUB_CUSTOM_ACPI}`
EOF
fi

9. Add executable bit to it:

$ sudo chmod +x /etc/grub.d/01_acpi

10. Copy the new dsdt.aml to /boot:

$ sudo cp dsdt.aml /boot

11. Regenerate grub.cfg:

$ sudo grub2-mkconfig -o /boot/grub2/grub.cfg

12. Reboot

References##

  1. Archwiki on DSDT
  2. Redhat's Bug Report
  3. Ubuntu's Bug Report 1
  4. Ubuntu's Bug Report 2
  5. Somebody's blog on fixing DSDT errors, remarks and warnings
  6. ACPICA Documentation
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