• Thomas Renninger's avatar
    ACPI: video: Ignore devices that aren't present in hardware · 22c13f9d
    Thomas Renninger authored
    This is a reimplemention of commit
    0119509c
    from Matthew Garrett <mjg59@srcf.ucam.org>
    
    This patch got removed because of a regression: ThinkPads with a
    Intel graphics card and an Integrated Graphics Device BIOS implementation
    stopped working.
    In fact, they only worked because the ACPI device of the discrete, the
    wrong one, got used (via int10). So ACPI functions were poking on the wrong
    hardware used which is a sever bug.
    The next patch provides support for above ThinkPads to be able to
    switch brightness via the legacy thinkpad_acpi driver and automatically
    detect when to use it.
    
    Original commit message from Matthew Garrett:
        Vendors often ship machines with a choice of integrated or discrete
        graphics, and use the same DSDT for both. As a result, the ACPI video
        module will locate devices that may not exist on this specific platform.
        Attempt to determine whether the device exists or not, and abort the
        device creation if it doesn't.
    
    http://bugzilla.kernel.org/show_bug.cgi?id=9614Signed-off-by: default avatarThomas Renninger <trenn@suse.de>
    Acked-by: default avatarZhang Rui <rui.zhang@intel.com>
    Signed-off-by: default avatarAndi Kleen <ak@linux.intel.com>
    Signed-off-by: default avatarLen Brown <len.brown@intel.com>
    22c13f9d
acpi_bus.h 11.3 KB