From: Harry Wentland <harry.wentland@amd.com>
To: Melissa Wen <mwen@igalia.com>,
airlied@gmail.com, alexander.deucher@amd.com,
christian.koenig@amd.com, simona@ffwll.ch, siqueira@igalia.com,
sunpeng.li@amd.com
Cc: kernel-dev@igalia.com, amd-gfx@lists.freedesktop.org,
dri-devel@lists.freedesktop.org
Subject: Re: [RFC PATCH 2/2] drm/amd/display: extend delta clamping logic to CM3 LUT helper
Date: Fri, 16 Jan 2026 15:27:59 -0500 [thread overview]
Message-ID: <a18c26d2-0664-4eb8-914b-52667fcc63f0@amd.com> (raw)
In-Reply-To: <20251208234741.293037-3-mwen@igalia.com>
On 2025-12-08 18:44, Melissa Wen wrote:
> Commit 27fc10d1095f ("drm/amd/display: Fix the delta clamping for shaper
> LUT") fixed banding when using plane shaper LUT in DCN10 CM helper. The
> problem is also present in DCN30 CM helper, fix banding by extending the
> same bug delta clamping fix to CM3.
>
> Signed-off-by: Melissa Wen <mwen@igalia.com>
Reviewed-by: Harry Wentland <harry.wentland@amd.com>
Harry
> ---
> .../amd/display/dc/dcn30/dcn30_cm_common.c | 30 +++++++++++++++----
> .../display/dc/dwb/dcn30/dcn30_cm_common.h | 2 +-
> .../amd/display/dc/hwss/dcn30/dcn30_hwseq.c | 9 +++---
> .../amd/display/dc/hwss/dcn32/dcn32_hwseq.c | 17 ++++++-----
> .../amd/display/dc/hwss/dcn401/dcn401_hwseq.c | 16 +++++-----
> 5 files changed, 49 insertions(+), 25 deletions(-)
>
> 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 ba20575be214..b1c2c8da1937 100644
> --- a/drivers/gpu/drm/amd/display/dc/dcn30/dcn30_cm_common.c
> +++ b/drivers/gpu/drm/amd/display/dc/dcn30/dcn30_cm_common.c
> @@ -105,9 +105,12 @@ void cm_helper_program_gamcor_xfer_func(
> #define NUMBER_REGIONS 32
> #define NUMBER_SW_SEGMENTS 16
>
> -bool cm3_helper_translate_curve_to_hw_format(
> - const struct dc_transfer_func *output_tf,
> - struct pwl_params *lut_params, bool fixpoint)
> +#define DC_LOGGER \
> + ctx->logger
> +
> +bool cm3_helper_translate_curve_to_hw_format(struct dc_context *ctx,
> + const struct dc_transfer_func *output_tf,
> + struct pwl_params *lut_params, bool fixpoint)
> {
> struct curve_points3 *corner_points;
> struct pwl_result_data *rgb_resulted;
> @@ -248,6 +251,10 @@ bool cm3_helper_translate_curve_to_hw_format(
> if (fixpoint == true) {
> i = 1;
> while (i != hw_points + 2) {
> + uint32_t red_clamp;
> + uint32_t green_clamp;
> + uint32_t blue_clamp;
> +
> if (i >= hw_points) {
> if (dc_fixpt_lt(rgb_plus_1->red, rgb->red))
> rgb_plus_1->red = dc_fixpt_add(rgb->red,
> @@ -260,9 +267,20 @@ bool cm3_helper_translate_curve_to_hw_format(
> rgb_minus_1->delta_blue);
> }
>
> - rgb->delta_red_reg = dc_fixpt_clamp_u0d10(rgb->delta_red);
> - rgb->delta_green_reg = dc_fixpt_clamp_u0d10(rgb->delta_green);
> - rgb->delta_blue_reg = dc_fixpt_clamp_u0d10(rgb->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);
> + rgb->delta_blue = dc_fixpt_sub(rgb_plus_1->blue, rgb->blue);
> +
> + red_clamp = dc_fixpt_clamp_u0d14(rgb->delta_red);
> + green_clamp = dc_fixpt_clamp_u0d14(rgb->delta_green);
> + blue_clamp = dc_fixpt_clamp_u0d14(rgb->delta_blue);
> +
> + if (red_clamp >> 10 || green_clamp >> 10 || blue_clamp >> 10)
> + DC_LOG_ERROR("Losing delta precision while programming shaper LUT.");
> +
> + rgb->delta_red_reg = red_clamp & 0x3ff;
> + rgb->delta_green_reg = green_clamp & 0x3ff;
> + rgb->delta_blue_reg = blue_clamp & 0x3ff;
> rgb->red_reg = dc_fixpt_clamp_u0d14(rgb->red);
> rgb->green_reg = dc_fixpt_clamp_u0d14(rgb->green);
> rgb->blue_reg = dc_fixpt_clamp_u0d14(rgb->blue);
> diff --git a/drivers/gpu/drm/amd/display/dc/dwb/dcn30/dcn30_cm_common.h b/drivers/gpu/drm/amd/display/dc/dwb/dcn30/dcn30_cm_common.h
> index b86347c9b038..95f9318a54ef 100644
> --- a/drivers/gpu/drm/amd/display/dc/dwb/dcn30/dcn30_cm_common.h
> +++ b/drivers/gpu/drm/amd/display/dc/dwb/dcn30/dcn30_cm_common.h
> @@ -59,7 +59,7 @@ void cm_helper_program_gamcor_xfer_func(
> const struct pwl_params *params,
> const struct dcn3_xfer_func_reg *reg);
>
> -bool cm3_helper_translate_curve_to_hw_format(
> +bool cm3_helper_translate_curve_to_hw_format(struct dc_context *ctx,
> const struct dc_transfer_func *output_tf,
> struct pwl_params *lut_params, bool fixpoint);
>
> diff --git a/drivers/gpu/drm/amd/display/dc/hwss/dcn30/dcn30_hwseq.c b/drivers/gpu/drm/amd/display/dc/hwss/dcn30/dcn30_hwseq.c
> index 81bcadf5e57e..f2d4cd527874 100644
> --- a/drivers/gpu/drm/amd/display/dc/hwss/dcn30/dcn30_hwseq.c
> +++ b/drivers/gpu/drm/amd/display/dc/hwss/dcn30/dcn30_hwseq.c
> @@ -239,7 +239,7 @@ bool dcn30_set_blend_lut(
> if (plane_state->blend_tf.type == TF_TYPE_HWPWL)
> blend_lut = &plane_state->blend_tf.pwl;
> else if (plane_state->blend_tf.type == TF_TYPE_DISTRIBUTED_POINTS) {
> - result = cm3_helper_translate_curve_to_hw_format(
> + result = cm3_helper_translate_curve_to_hw_format(plane_state->ctx,
> &plane_state->blend_tf, &dpp_base->regamma_params, false);
> if (!result)
> return result;
> @@ -334,8 +334,9 @@ bool dcn30_set_input_transfer_func(struct dc *dc,
> if (plane_state->in_transfer_func.type == TF_TYPE_HWPWL)
> params = &plane_state->in_transfer_func.pwl;
> else if (plane_state->in_transfer_func.type == TF_TYPE_DISTRIBUTED_POINTS &&
> - cm3_helper_translate_curve_to_hw_format(&plane_state->in_transfer_func,
> - &dpp_base->degamma_params, false))
> + cm3_helper_translate_curve_to_hw_format(plane_state->ctx,
> + &plane_state->in_transfer_func,
> + &dpp_base->degamma_params, false))
> params = &dpp_base->degamma_params;
>
> result = dpp_base->funcs->dpp_program_gamcor_lut(dpp_base, params);
> @@ -406,7 +407,7 @@ bool dcn30_set_output_transfer_func(struct dc *dc,
> params = &stream->out_transfer_func.pwl;
> else if (pipe_ctx->stream->out_transfer_func.type ==
> TF_TYPE_DISTRIBUTED_POINTS &&
> - cm3_helper_translate_curve_to_hw_format(
> + cm3_helper_translate_curve_to_hw_format(stream->ctx,
> &stream->out_transfer_func,
> &mpc->blender_params, false))
> params = &mpc->blender_params;
> diff --git a/drivers/gpu/drm/amd/display/dc/hwss/dcn32/dcn32_hwseq.c b/drivers/gpu/drm/amd/display/dc/hwss/dcn32/dcn32_hwseq.c
> index b213a2ac827a..27abc08918bc 100644
> --- a/drivers/gpu/drm/amd/display/dc/hwss/dcn32/dcn32_hwseq.c
> +++ b/drivers/gpu/drm/amd/display/dc/hwss/dcn32/dcn32_hwseq.c
> @@ -486,8 +486,9 @@ bool dcn32_set_mcm_luts(
> if (plane_state->blend_tf.type == TF_TYPE_HWPWL)
> lut_params = &plane_state->blend_tf.pwl;
> else if (plane_state->blend_tf.type == TF_TYPE_DISTRIBUTED_POINTS) {
> - result = cm3_helper_translate_curve_to_hw_format(&plane_state->blend_tf,
> - &dpp_base->regamma_params, false);
> + result = cm3_helper_translate_curve_to_hw_format(plane_state->ctx,
> + &plane_state->blend_tf,
> + &dpp_base->regamma_params, false);
> if (!result)
> return result;
>
> @@ -502,8 +503,9 @@ bool dcn32_set_mcm_luts(
> else if (plane_state->in_shaper_func.type == TF_TYPE_DISTRIBUTED_POINTS) {
> // TODO: dpp_base replace
> ASSERT(false);
> - cm3_helper_translate_curve_to_hw_format(&plane_state->in_shaper_func,
> - &dpp_base->shaper_params, true);
> + cm3_helper_translate_curve_to_hw_format(plane_state->ctx,
> + &plane_state->in_shaper_func,
> + &dpp_base->shaper_params, true);
> lut_params = &dpp_base->shaper_params;
> }
>
> @@ -543,8 +545,9 @@ bool dcn32_set_input_transfer_func(struct dc *dc,
> if (plane_state->in_transfer_func.type == TF_TYPE_HWPWL)
> params = &plane_state->in_transfer_func.pwl;
> else if (plane_state->in_transfer_func.type == TF_TYPE_DISTRIBUTED_POINTS &&
> - cm3_helper_translate_curve_to_hw_format(&plane_state->in_transfer_func,
> - &dpp_base->degamma_params, false))
> + cm3_helper_translate_curve_to_hw_format(plane_state->ctx,
> + &plane_state->in_transfer_func,
> + &dpp_base->degamma_params, false))
> params = &dpp_base->degamma_params;
>
> dpp_base->funcs->dpp_program_gamcor_lut(dpp_base, params);
> @@ -575,7 +578,7 @@ bool dcn32_set_output_transfer_func(struct dc *dc,
> params = &stream->out_transfer_func.pwl;
> else if (pipe_ctx->stream->out_transfer_func.type ==
> TF_TYPE_DISTRIBUTED_POINTS &&
> - cm3_helper_translate_curve_to_hw_format(
> + cm3_helper_translate_curve_to_hw_format(stream->ctx,
> &stream->out_transfer_func,
> &mpc->blender_params, false))
> params = &mpc->blender_params;
> diff --git a/drivers/gpu/drm/amd/display/dc/hwss/dcn401/dcn401_hwseq.c b/drivers/gpu/drm/amd/display/dc/hwss/dcn401/dcn401_hwseq.c
> index 2fbc22afb89c..5eda7648d0d2 100644
> --- a/drivers/gpu/drm/amd/display/dc/hwss/dcn401/dcn401_hwseq.c
> +++ b/drivers/gpu/drm/amd/display/dc/hwss/dcn401/dcn401_hwseq.c
> @@ -430,7 +430,7 @@ void dcn401_populate_mcm_luts(struct dc *dc,
> if (mcm_luts.lut1d_func->type == TF_TYPE_HWPWL)
> m_lut_params.pwl = &mcm_luts.lut1d_func->pwl;
> else if (mcm_luts.lut1d_func->type == TF_TYPE_DISTRIBUTED_POINTS) {
> - rval = cm3_helper_translate_curve_to_hw_format(
> + rval = cm3_helper_translate_curve_to_hw_format(mpc->ctx,
> mcm_luts.lut1d_func,
> &dpp_base->regamma_params, false);
> m_lut_params.pwl = rval ? &dpp_base->regamma_params : NULL;
> @@ -450,7 +450,7 @@ void dcn401_populate_mcm_luts(struct dc *dc,
> m_lut_params.pwl = &mcm_luts.shaper->pwl;
> else if (mcm_luts.shaper->type == TF_TYPE_DISTRIBUTED_POINTS) {
> ASSERT(false);
> - rval = cm3_helper_translate_curve_to_hw_format(
> + rval = cm3_helper_translate_curve_to_hw_format(mpc->ctx,
> mcm_luts.shaper,
> &dpp_base->regamma_params, true);
> m_lut_params.pwl = rval ? &dpp_base->regamma_params : NULL;
> @@ -627,8 +627,9 @@ bool dcn401_set_mcm_luts(struct pipe_ctx *pipe_ctx,
> if (plane_state->blend_tf.type == TF_TYPE_HWPWL)
> lut_params = &plane_state->blend_tf.pwl;
> else if (plane_state->blend_tf.type == TF_TYPE_DISTRIBUTED_POINTS) {
> - rval = cm3_helper_translate_curve_to_hw_format(&plane_state->blend_tf,
> - &dpp_base->regamma_params, false);
> + rval = cm3_helper_translate_curve_to_hw_format(plane_state->ctx,
> + &plane_state->blend_tf,
> + &dpp_base->regamma_params, false);
> lut_params = rval ? &dpp_base->regamma_params : NULL;
> }
> result = mpc->funcs->program_1dlut(mpc, lut_params, mpcc_id);
> @@ -639,8 +640,9 @@ bool dcn401_set_mcm_luts(struct pipe_ctx *pipe_ctx,
> lut_params = &plane_state->in_shaper_func.pwl;
> else if (plane_state->in_shaper_func.type == TF_TYPE_DISTRIBUTED_POINTS) {
> // TODO: dpp_base replace
> - rval = cm3_helper_translate_curve_to_hw_format(&plane_state->in_shaper_func,
> - &dpp_base->shaper_params, true);
> + rval = cm3_helper_translate_curve_to_hw_format(plane_state->ctx,
> + &plane_state->in_shaper_func,
> + &dpp_base->shaper_params, true);
> lut_params = rval ? &dpp_base->shaper_params : NULL;
> }
> result &= mpc->funcs->program_shaper(mpc, lut_params, mpcc_id);
> @@ -674,7 +676,7 @@ bool dcn401_set_output_transfer_func(struct dc *dc,
> params = &stream->out_transfer_func.pwl;
> else if (pipe_ctx->stream->out_transfer_func.type ==
> TF_TYPE_DISTRIBUTED_POINTS &&
> - cm3_helper_translate_curve_to_hw_format(
> + cm3_helper_translate_curve_to_hw_format(stream->ctx,
> &stream->out_transfer_func,
> &mpc->blender_params, false))
> params = &mpc->blender_params;
next prev parent reply other threads:[~2026-01-16 20:28 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-12-08 23:44 [RFC PATCH 0/2] Fixes on CM3 helper for plane shaper LUT Melissa Wen
2025-12-08 23:44 ` [RFC PATCH 1/2] drm/amd/display: fix wrong color value mapping on DCN32 " Melissa Wen
2026-01-16 20:29 ` Harry Wentland
2026-01-16 23:54 ` Alex Hung
2025-12-08 23:44 ` [RFC PATCH 2/2] drm/amd/display: extend delta clamping logic to CM3 LUT helper Melissa Wen
2026-01-16 20:27 ` Harry Wentland [this message]
2026-01-16 23:52 ` Alex Hung
2025-12-09 1:34 ` [RFC PATCH 0/2] Fixes on CM3 helper for plane shaper LUT Matthew Schwartz
2025-12-09 14:31 ` Melissa Wen
2025-12-09 14:44 ` Melissa Wen
2025-12-09 15:12 ` Harry Wentland
2025-12-09 15:18 ` Melissa Wen
2025-12-09 18:19 ` Matthew Schwartz
2025-12-10 20:46 ` Melissa Wen
2025-12-10 20:56 ` Matthew Schwartz
2026-01-16 17:08 ` Melissa Wen
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