• Hans de Goede's avatar
    ACPI: video: Add backlight=native quirk for Dell OptiPlex 5480 AIO · ac78288f
    Hans de Goede authored
    Dell All In One (AIO) models released after 2017 may use a backlight
    controller board connected to an UART.
    
    In DSDT this uart port will be defined as:
    
       Name (_HID, "DELL0501")
       Name (_CID, EisaId ("PNP0501")
    
    The Dell OptiPlex 5480 AIO has an ACPI device for one of its UARTs with
    the above _HID + _CID. Loading the dell-uart-backlight driver fails with
    the following errors:
    
    [   18.261353] dell_uart_backlight serial0-0: Timed out waiting for response.
    [   18.261356] dell_uart_backlight serial0-0: error -ETIMEDOUT: getting firmware version
    [   18.261359] dell_uart_backlight serial0-0: probe with driver dell_uart_backlight failed with error -110
    
    Indicating that there is no backlight controller board attached to
    the UART, while the GPU's native backlight control method does work.
    
    Add a quirk to use the GPU's native backlight control method on this model.
    
    Fixes: cd8e468e ("ACPI: video: Add Dell UART backlight controller detection")
    Cc: All applicable <stable@vger.kernel.org>
    Signed-off-by: default avatarHans de Goede <hdegoede@redhat.com>
    Link: https://patch.msgid.link/20240918153849.37221-1-hdegoede@redhat.com
    [ rjw: Changelog edit ]
    Signed-off-by: default avatarRafael J. Wysocki <rafael.j.wysocki@intel.com>
    ac78288f
video_detect.c 28.3 KB