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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 7760 AIO has an ACPI device for one if its UARTs with
the above _HID + _CID. Loading the dell-uart-backlight driver shows that
there actually is a backlight controller board attached to the UART,
which reports a firmware version of "G&MX01-V15".

But the backlight controller board does not actually control the backlight
brightness and 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: 484bae9e ("platform/x86: Add new Dell UART backlight driver")
Closes: https://bugzilla.redhat.com/show_bug.cgi?id=2303936


Cc: All applicable <stable@vger.kernel.org>
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Reviewed-by: Andy Shevch...