This adds support for controlling panel backlights over eDP using VESA's standard backlight control interface. Luckily, Nvidia was cool enough to never come up with their own proprietary backlight control interface (at least, not any that I or the laptop manufacturers I've talked to are aware of), so this should work for any laptop panels which support the VESA backlight control interface. Note that we don't yet provide the panel backlight frequency to the DRM DP backlight helpers. This should be fine for the time being, since it's not required to get basic backlight controls working. For reference: there's some mentions of PWM backlight values in nouveau_reg.h, but I'm not sure these are the values we would want to use. If we figure out how to get this information in the future, we'll have the benefit of more granular backlight control. Signed-off-by: Lyude Paul <lyude@redhat.com> Reviewed-by: Ben Skeggs <bskeggs@redhat.com> Cc: Jani Nikula <jani.nikula@intel.com> Cc: Dave Airlie <airlied@gmail.com> Cc: greg.depoire@gmail.com Link: https://patchwork.freedesktop.org/patch/msgid/20210514181504.565252-10-lyude@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.
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