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[ Upstream commit 4f7f96453b462b3de0fa18d18fe983960bb5ee7f ] Some machines change the brightness themselves when a brightness hotkey gets pressed, despite us telling them not to. This causes the brightness to go two steps up / down when the hotkey is pressed. This is esp. a problem on older machines with only a few brightness levels. This commit adds a new hw_changes_brightness quirk which makes acpi_video_device_notify() only call backlight_force_update(..., BACKLIGHT_UPDATE_HOTKEY) and not do anything else, notifying userspace that the brightness was changed and leaving it at that fixing the dual step problem. BugLink: https://bugzilla.kernel.org/show_bug.cgi?id=204077 Reported-by: Kacper Piwiński <cosiekvfj@o2.pl> Tested-by: Kacper Piwiński <cosiekvfj@o2.pl> Signed-off-by: Hans de Goede <hdegoede@redhat.com> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> Signed-off-by: Sasha Levin <sashal@kernel.org>
Linux kernel ============ This file was moved to Documentation/admin-guide/README.rst Please notice that there are several guides for kernel developers and users. These guides can be rendered in a number of formats, like HTML and PDF. In order to build the documentation, use ``make htmldocs`` or ``make pdfdocs``. There are various text files in the Documentation/ subdirectory, several of them using the Restructured Text markup notation. See Documentation/00-INDEX for a list of what is contained in each file. 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.