drm/i915/glk: Improve rounding caused by pre-CSC gamma tables
The 33rd entry in the pre-CSC gamma table in Geminilake can represent a value of 1.0 as 17 bits fixed point with one integer bit. However, the table was generated such that the value of 1.0 would be 0.ffff with all the intervals scaled accordingly. For instance, 0.5 mapped to 0.7fff instead of 0.8000. For a reason that is not clear to the author, the rounding seems to be different when a cursor plane is used, leading to some seemingly random failures of the kms_cursor_crc igt tests. The differences weren't perceptible at 8bpc with images captured by a Chamelium device, but did cause CRC mismatches. Signed-off-by: NAnder Conselvan de Oliveira <ander.conselvan.de.oliveira@intel.com> Reviewed-by: NVille Syrjälä <ville.syrjala@linux.intel.com> Link: http://patchwork.freedesktop.org/patch/msgid/20170310101835.29845-1-ander.conselvan.de.oliveira@intel.com
Showing
想要评论请 注册 或 登录