What is it?

This is a tool to create an initrd with fixed DSDT and SSDT3 ACPI tables for Dell XPS 15 7590

XPS 15 7590 has two issues with its ACPI tables:

1. SSDT3 has Stall(250) call which violates ACPI spec resulting in Linux complaining:

ACPI Warning: Time parameter 250 us > 100 us violating ACPI spec, please fix the firmware. (20230628/exsystem-141)

The fix is to replace Stall(250) with Sleep(250)

2. DSDT has missing symbol \_SB.PCI0.PEG0.PEGP.BRT6.LCD at least on models with OLED screen, so if when you use the keys to increase/decrease screen brightness, ACPI interpreter complains:

ACPI BIOS Error (bug): Could not resolve symbol [\_SB.PCI0.PEG0.PEGP.BRT6.LCD], AE_NOT_FOUND (20230628/psargs-330)
ACPI Error: Aborting method \_SB.PCI0.PEG0.PEGP.BRT6 due to previous error (AE_NOT_FOUND) (20230628/psparse-529)
ACPI Error: Aborting method \EV5 due to previous error (AE_NOT_FOUND) (20230628/psparse-529)
ACPI Error: Aborting method \SMEE due to previous error (AE_NOT_FOUND) (20230628/psparse-529)
ACPI Error: Aborting method \SMIE due to previous error (AE_NOT_FOUND) (20230628/psparse-529)
ACPI Error: Aborting method \NEVT due to previous error (AE_NOT_FOUND) (20230628/psparse-529)

The fix is to skip calling \_SB.PCI0.PEG0.PEGP.BRT6 method

How to use

If you previously used the tool and booted with patched_acpi_tables.cpio initrd, edit your bootloader configuration to disable it, since the tool needs unpatched DSDT and SSDT3 tables.

Run make all, it will create patched_acpi_tables.cpio that can be used to patch ACPI tables in Linux in runtime, just add it as the first initrd in your bootloader config. Please refer to your bootloader documentation on how to do so.

Note: it is important to rebuild patched_acpi_tables.cpio each time after you update the BIOS.