drm/i915/gen9, gen10: Disable FBC on planes with a misaligned Y-offset
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
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