ICL introduces a new gamma correction mode in display engine, called
multi-segmented-gamma mode. This mode allows users to program the
darker region of the gamma curve with sueprfine precision. An
example use case for this is HDR curves (like PQ ST-2084).
If we plot a gamma correction curve from value range between 0.0 to 1.0,
ICL's multi-segment has 3 different sections:
- superfine segment: 9 values, ranges between 0 - 1/(128 * 256)
- fine segment: 257 values, ranges between 0 - 1/(128)
- corase segment: 257 values, ranges between 0 - 1
This patch:
- Changes gamma LUTs size for ICL/GEN11 to 262144 entries (8 * 128 * 256),
so that userspace can program with highest precision supported.
- Changes default gamma mode (non-legacy) to multi-segmented-gamma mode.
- Adds functions to program/detect multi-segment gamma.
V2: Addressed review comments from Ville
- separate function for superfine and fine segments.
- remove enum for segments.
- reuse last entry of the LUT as gc_max value.
- replace if() ....cond with switch...case in icl_load_luts.
- add an entry variable, instead of 'word'
V3: Addressed review comments from Ville
- extra newline
- s/entry/color/
- remove LUT size checks
- program ilk_lut_12p4_ldw value before ilk_lut_12p4_udw
- Change the comments in description of fine and coarse segments,
and try to make more sense.
- use 8 * 128 instead of 1024
- add 1 entry in LUT for GCMAX
V4: Addressed review comments from Ville
- Remove unused macro
- missing shift entry in blue
- pick correct entry for GCMAX
- Added Ville's R-B
Note: Tested and confirmed the programming sequence of odd/even
registers in the HW. The correct sequence should be:
ilk_lut_12p4_udw
ilk_lut_12p4_ldw
v5: Addressed Ville's review comments and renamed odd/even register
helpers to be more consistent with the values.
Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
Cc: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Suggested-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Signed-off-by: Shashank Sharma <shashank.sharma@intel.com>
Signed-off-by: Uma Shankar <uma.shankar@intel.com>
Signed-off-by: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/1560321900-18318-5-git-send-email-uma.shankar@intel.com
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