diff options
| -rw-r--r-- | include/drm/drm_color_mgmt.h | 19 |
1 files changed, 8 insertions, 11 deletions
diff --git a/include/drm/drm_color_mgmt.h b/include/drm/drm_color_mgmt.h index 81c298488b0c..54b2b2467bfd 100644 --- a/include/drm/drm_color_mgmt.h +++ b/include/drm/drm_color_mgmt.h @@ -36,20 +36,17 @@ struct drm_plane; * * Extract a degamma/gamma LUT value provided by user (in the form of * &drm_color_lut entries) and round it to the precision supported by the - * hardware. + * hardware, following OpenGL int<->float conversion rules + * (see eg. OpenGL 4.6 specification - 2.3.5 Fixed-Point Data Conversions). */ static inline u32 drm_color_lut_extract(u32 user_input, int bit_precision) { - u32 val = user_input; - u32 max = 0xffff >> (16 - bit_precision); - - /* Round only if we're not using full precision. */ - if (bit_precision < 16) { - val += 1UL << (16 - bit_precision - 1); - val >>= 16 - bit_precision; - } - - return clamp_val(val, 0, max); + if (bit_precision > 16) + return DIV_ROUND_CLOSEST_ULL(mul_u32_u32(user_input, (1 << bit_precision) - 1), + (1 << 16) - 1); + else + return DIV_ROUND_CLOSEST(user_input * ((1 << bit_precision) - 1), + (1 << 16) - 1); } u64 drm_color_ctm_s31_32_to_qm_n(u64 user_input, u32 m, u32 n); |