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Enabling FBC on a plane having a Y-offset that isn't divisible by 4 may cause pipe FIFO underruns and flickers, so disable FBC on such a config. I tried the followings to work around the issue: - enable each HW work around in ILK_DPFC_CHICKEN - disable each compression algorithm in ILK_DPFC_CONTROL - disable low-power watermarks None of the above got rid of the problem. I haven't found this issue in the Bspec/WA database either. Besides the igt testcase below (yet to be merged) an easy way to reproduce the issue is to enable a plane with FBC and a plane Y-offset not aligned to 4 and then just enable/disable FBC in a loop, keeping the plane enabled. I could trigger the problem on BXT/GLK/SKL/CNL, so assume for now that it's only present on GEN9 and GEN10. v2: (Ville) - Run the test/apply the WA on CNL as well. - Use IS_GEN() instead of INTEL_GEN(). - Fix spelling. Cc: Paulo Zanoni <paulo.r.zanoni@intel.com> Cc: Ville Syrjälä <ville.syrjala@linux.intel.com> Testcase: igt/kms_plane/plane-clipping-pipe-A-planes Signed-off-by: Imre Deak <imre.deak@intel.com> Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com> Link: https://patchwork.freedesktop.org/patch/msgid/20180301134457.13974-1-imre.deak@intel.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.