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Hardware understands the regamma LUT as a piecewise linear function, with points spaced exponentially along the range. We previously programmed the LUT for range [2^-10, 2^0). This causes (normalized) color values of 1 (=2^0) to miss the programmed LUT, and fall onto the end region. For DCE, the end region is extrapolated using a single (base, slope) pair, using the max y-value from the last point in the curve as base. This presents a problem, since this value affects all three color channels. Scaling down the intensity of say - the blue regamma curve - will not affect it's end region. This is especially noticiable when using RedShift. It scales down the blue and green channels, but leaves full-intensity colors unshifted. Therefore, extend the range to cover [2^-10, 2^1) by programming another hardware segment, containing only one point. That way, we won't be hitting the end region. Note that things are a bit different for DCN, since the end region can be set per-channel. Signed-off-by: Leo (Sunpeng) Li <sunpeng.li@amd.com> Reviewed-by: Krunoslav Kovac <Krunoslav.Kovac@amd.com> Acked-by: Harry Wentland <harry.wentland@amd.com> Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
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.