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Hans de Goede
ac78288fe0
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: cd8e468efb ("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>
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the reStructuredText markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.