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On MacBook Pros introduced 2011 and onward, external DP ports are combined DP/Thunderbolt ports that are no longer fully switchable between GPUs, they can only be driven by the discrete GPU. More specifically, the Main Link pins (which transport the actual video and audio streams) are soldered to the discrete GPU, whereas the AUX Channel pins are switchable. Because the integrated GPU is missing the Main Link, external displays appear to it as phantoms which fail to link-train. Force the AUX channel to the discrete GPU on these models to avoid any confusion. Document the switching policy implemented by this commit. Acked-by: Andy Shevchenko <andy.shevchenko@gmail.com> Signed-off-by: Lukas Wunner <lukas@wunner.de> Link: http://patchwork.freedesktop.org/patch/msgid/4d1fcc92d1960049e2cff997fbd2d74e45e84e49.1489145162.git.lukas@wunner.de
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.