This is a note to let you know that I've just added the patch titled drm/amd/display: Correct algorithm for reversed gamma to the 5.10-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary The filename of the patch is: drm-amd-display-correct-algorithm-for-reversed-gamma.patch and it can be found in the queue-5.10 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let <stable@xxxxxxxxxxxxxxx> know about it. >From 34fa493a565cc6fcee6919787c11e264f55603c6 Mon Sep 17 00:00:00 2001 From: Calvin Hou <Calvin.Hou@xxxxxxx> Date: Tue, 2 Mar 2021 10:48:26 -0500 Subject: drm/amd/display: Correct algorithm for reversed gamma From: Calvin Hou <Calvin.Hou@xxxxxxx> commit 34fa493a565cc6fcee6919787c11e264f55603c6 upstream. [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@xxxxxxx> Signed-off-by: Calvin Hou <Calvin.Hou@xxxxxxx> Reviewed-by: Jun Lei <Jun.Lei@xxxxxxx> Reviewed-by: Krunoslav Kovac <Krunoslav.Kovac@xxxxxxx> Acked-by: Solomon Chiu <solomon.chiu@xxxxxxx> Acked-by: Vladimir Stempen <Vladimir.Stempen@xxxxxxx> Signed-off-by: Alex Deucher <alexander.deucher@xxxxxxx> Cc: stable@xxxxxxxxxxxxxxx Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- drivers/gpu/drm/amd/display/dc/dcn30/dcn30_cm_common.c | 26 +++++++++++------ 1 file changed, 18 insertions(+), 8 deletions(-) --- 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_fo 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_fo 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_fo 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_fo 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_fo 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_fo } ++rgb_plus_1; + rgb_minus_1 = rgb; ++rgb; ++i; } Patches currently in stable-queue which might be from Calvin.Hou@xxxxxxx are queue-5.10/drm-amd-display-correct-algorithm-for-reversed-gamma.patch