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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: Hans de Goede <hdegoede@redhat.com> Link: https://patch.msgid.link/20240918153849.37221-1-hdegoede@redhat.com [ rjw: Changelog edit ] Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
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