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| author | Leo (Sunpeng) Li <sunpeng.li@amd.com> | 2018-04-03 16:07:16 -0400 |
|---|---|---|
| committer | Alex Deucher <alexander.deucher@amd.com> | 2018-04-12 13:56:21 -0500 |
| commit | b2f3f5920ddb5b121cbc57ee9efc0c1ffe4d19af (patch) | |
| tree | 7c3ac77552268f65a03c214c12864a67bda1d013 /drivers/gpu | |
| parent | 1409bc6b2bff44ea4e366b892dcac4a1cf0a5e8b (diff) | |
| download | linux-b2f3f5920ddb5b121cbc57ee9efc0c1ffe4d19af.tar.gz linux-b2f3f5920ddb5b121cbc57ee9efc0c1ffe4d19af.tar.xz | |
drm/amd/display: Fix regamma not affecting full-intensity color values
Hardware understands the regamma LUT as a piecewise linear function,
with points spaced exponentially along the range. We previously
programmed the LUT for range [2^-10, 2^0). This causes (normalized)
color values of 1 (=2^0) to miss the programmed LUT, and fall onto the
end region.
For DCE, the end region is extrapolated using a single (base, slope)
pair, using the max y-value from the last point in the curve as base.
This presents a problem, since this value affects all three color
channels. Scaling down the intensity of say - the blue regamma curve -
will not affect it's end region. This is especially noticiable when
using RedShift. It scales down the blue and green channels, but leaves
full-intensity colors unshifted.
Therefore, extend the range to cover [2^-10, 2^1) by programming another
hardware segment, containing only one point. That way, we won't be
hitting the end region.
Note that things are a bit different for DCN, since the end region can
be set per-channel.
Signed-off-by: Leo (Sunpeng) Li <sunpeng.li@amd.com>
Reviewed-by: Krunoslav Kovac <Krunoslav.Kovac@amd.com>
Acked-by: Harry Wentland <harry.wentland@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Diffstat (limited to 'drivers/gpu')
| -rw-r--r-- | drivers/gpu/drm/amd/display/dc/dce110/dce110_hw_sequencer.c | 9 |
1 files changed, 6 insertions, 3 deletions
diff --git a/drivers/gpu/drm/amd/display/dc/dce110/dce110_hw_sequencer.c b/drivers/gpu/drm/amd/display/dc/dce110/dce110_hw_sequencer.c index 1c644c7a24b7..d0575999f172 100644 --- a/drivers/gpu/drm/amd/display/dc/dce110/dce110_hw_sequencer.c +++ b/drivers/gpu/drm/amd/display/dc/dce110/dce110_hw_sequencer.c @@ -453,10 +453,13 @@ dce110_translate_regamma_to_hw_format(const struct dc_transfer_func *output_tf, } else { /* 10 segments - * segment is from 2^-10 to 2^0 + * segment is from 2^-10 to 2^1 + * We include an extra segment for range [2^0, 2^1). This is to + * ensure that colors with normalized values of 1 don't miss the + * LUT. */ region_start = -10; - region_end = 0; + region_end = 1; seg_distr[0] = 4; seg_distr[1] = 4; @@ -468,7 +471,7 @@ dce110_translate_regamma_to_hw_format(const struct dc_transfer_func *output_tf, seg_distr[7] = 4; seg_distr[8] = 4; seg_distr[9] = 4; - seg_distr[10] = -1; + seg_distr[10] = 0; seg_distr[11] = -1; seg_distr[12] = -1; seg_distr[13] = -1; |