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drm/amd/display: Correct algorithm for reversed gamma
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[Why]
DCN30 needs to correctly program reversed gamma curve, which DCN20
already has.
Also needs to fix a bug that 252-255 values are clipped.

[How]
Apply two fixes into DCN30.

Bug: https://gitlab.freedesktop.org/drm/amd/-/issues/1513
Tested-by: Daniel Wheeler <daniel.wheeler@amd.com>
Signed-off-by: Calvin Hou <Calvin.Hou@amd.com>
Reviewed-by: Jun Lei <Jun.Lei@amd.com>
Reviewed-by: Krunoslav Kovac <Krunoslav.Kovac@amd.com>
Acked-by: Solomon Chiu <solomon.chiu@amd.com>
Acked-by: Vladimir Stempen <Vladimir.Stempen@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Cc: stable@vger.kernel.org
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Calvin Hou authored and Alex Deucher committed Mar 18, 2021
1 parent 7307679 commit 34fa493
Showing 1 changed file with 18 additions and 8 deletions.
26 changes: 18 additions & 8 deletions drivers/gpu/drm/amd/display/dc/dcn30/dcn30_cm_common.c
Original file line number Diff line number Diff line change
@@ -113,6 +113,7 @@ bool cm3_helper_translate_curve_to_hw_format(
struct pwl_result_data *rgb_resulted;
struct pwl_result_data *rgb;
struct pwl_result_data *rgb_plus_1;
struct pwl_result_data *rgb_minus_1;
struct fixed31_32 end_value;

int32_t region_start, region_end;
@@ -140,7 +141,7 @@ bool cm3_helper_translate_curve_to_hw_format(
region_start = -MAX_LOW_POINT;
region_end = NUMBER_REGIONS - MAX_LOW_POINT;
} else {
/* 10 segments
/* 11 segments
* segment is from 2^-10 to 2^0
* There are less than 256 points, for optimization
*/
@@ -154,9 +155,10 @@ bool cm3_helper_translate_curve_to_hw_format(
seg_distr[7] = 4;
seg_distr[8] = 4;
seg_distr[9] = 4;
seg_distr[10] = 1;

region_start = -10;
region_end = 0;
region_end = 1;
}

for (i = region_end - region_start; i < MAX_REGIONS_NUMBER ; i++)
@@ -189,6 +191,10 @@ bool cm3_helper_translate_curve_to_hw_format(
rgb_resulted[hw_points - 1].green = output_tf->tf_pts.green[start_index];
rgb_resulted[hw_points - 1].blue = output_tf->tf_pts.blue[start_index];

rgb_resulted[hw_points].red = rgb_resulted[hw_points - 1].red;
rgb_resulted[hw_points].green = rgb_resulted[hw_points - 1].green;
rgb_resulted[hw_points].blue = rgb_resulted[hw_points - 1].blue;

// All 3 color channels have same x
corner_points[0].red.x = dc_fixpt_pow(dc_fixpt_from_int(2),
dc_fixpt_from_int(region_start));
@@ -259,15 +265,18 @@ bool cm3_helper_translate_curve_to_hw_format(

rgb = rgb_resulted;
rgb_plus_1 = rgb_resulted + 1;
rgb_minus_1 = rgb;

i = 1;
while (i != hw_points + 1) {
if (dc_fixpt_lt(rgb_plus_1->red, rgb->red))
rgb_plus_1->red = rgb->red;
if (dc_fixpt_lt(rgb_plus_1->green, rgb->green))
rgb_plus_1->green = rgb->green;
if (dc_fixpt_lt(rgb_plus_1->blue, rgb->blue))
rgb_plus_1->blue = rgb->blue;
if (i >= hw_points - 1) {
if (dc_fixpt_lt(rgb_plus_1->red, rgb->red))
rgb_plus_1->red = dc_fixpt_add(rgb->red, rgb_minus_1->delta_red);
if (dc_fixpt_lt(rgb_plus_1->green, rgb->green))
rgb_plus_1->green = dc_fixpt_add(rgb->green, rgb_minus_1->delta_green);
if (dc_fixpt_lt(rgb_plus_1->blue, rgb->blue))
rgb_plus_1->blue = dc_fixpt_add(rgb->blue, rgb_minus_1->delta_blue);
}

rgb->delta_red = dc_fixpt_sub(rgb_plus_1->red, rgb->red);
rgb->delta_green = dc_fixpt_sub(rgb_plus_1->green, rgb->green);
@@ -283,6 +292,7 @@ bool cm3_helper_translate_curve_to_hw_format(
}

++rgb_plus_1;
rgb_minus_1 = rgb;
++rgb;
++i;
}

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