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3608a2cd81
On some MacBooks both the apple_bl and the apple-gmux backlight drivers may be able to export a /sys/class/backlight device. To avoid having 2 backlight devices for one LCD panel until now the apple-gmux driver has been calling apple_bl_unregister() to move the apple_bl backlight device out of the way when it loads. Similar problems exist on other x86 laptops and all backlight drivers which may be used on x86 laptops have moved to using acpi_video_get_backlight_type() to determine whether they should load or not. Switch apple_bl to this model too, so that it is consistent with all the other x86 backlight drivers. Besides code-simplification and consistency this has 2 other benefits: 1) It removes a race during boot where userspace will briefly see an apple_bl backlight and then have it disappear again, leading to e.g.: https://bbs.archlinux.org/viewtopic.php?id=269920 2) This allows user to switch between the drivers by passing acpi_backlight=apple_gmux or acpi_backlight=vendor on the kernel commandline. Signed-off-by: Hans de Goede <hdegoede@redhat.com> Reviewed-by: Daniel Thompson <daniel.thompson@linaro.org> Acked-by: Lee Jones <lee@kernel.org> Link: https://lore.kernel.org/r/20230307120540.389920-1-hdegoede@redhat.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 Restructured Text 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.