IdeaPad Y470 ACPI bug

Discussion in 'BIOS Mods' started by Fang, Jun 7, 2012.

  1. Fang

    Fang MDL Novice

    Jun 6, 2012
    #1 Fang, Jun 7, 2012
    Last edited: Jun 7, 2012
    I wonder how to fix ACPI bug in Y470 ? /without patching Linux kernel, I mean by modifying BIOS its-self./

    On the Lenovo Ideapad Y470 and Lenovo Ideapad Y570, the kernel assigns the \_SB.PCI0.PEG0.VGA handle to the PCI device (possibly because the _DOS method is found on the handle?) However, the correct _DSM, _ROM, _PS0 and _PS3 can be found on the \_SB.PCI0.PEG0.PEGP handle. _PSx on the VGA handle is basically a no-op, it only gets/sets the _PSC variable. _ROM does not exist and the _DSM method is not useful comparing it to the PEGP._DSM method. Due to this issue, the nouveau driver fails to load the vbios (because _ROM does not exist on VGA). Similarly, the proprietary nvidia driver fails to load. As for the _PS0 and _PS0 methods, using the pci_set_power_state methods does not really disable the PCI device.