drm/amd/display: Correct algorithm for reversed gamma

[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

diff --git a/drivers/gpu/drm/amd/display/dc/dcn30/dcn30_cm_common.c b/drivers/gpu/drm/amd/display/dc/dcn30/dcn30_cm_common.c
index 41a1d0e..e0df9b0 100644 (file)
--- a/drivers/gpu/drm/amd/display/dc/dcn30/dcn30_cm_common.c
+++ b/drivers/gpu/drm/amd/display/dc/dcn30/dcn30_cm_common.c
@@ -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;
        }