drm/amd/display: Implement custom degamma lut on dcn

[Why]
Custom degamma lut functions are a feature we would
like to support on compatible hardware

[How]
In atomic check, convert from array of drm_color_lut to
dc_transfer_func.  On hardware commit, allow for possibility
of custom degamma.  Both are based on the equivalent
regamma pipeline.
Signed-off-by: David Francis <David.Francis@amd.com>
Reviewed-by: Krunoslav Kovac <Krunoslav.Kovac@amd.com>
Acked-by: Bhawanpreet Lakha <Bhawanpreet.Lakha@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_color.c

@@ -231,18 +231,21 @@ void amdgpu_dm_set_ctm(struct dm_crtc_state *crtc)
  * preparation for hardware commit. If no lut is specified by user, we default
  * to SRGB degamma.
  *
- * Currently, we only support degamma bypass, or preprogrammed SRGB degamma.
- * Programmable degamma is not supported, and an attempt to do so will return
- * -EINVAL.
+ * We support degamma bypass, predefined SRGB, and custom degamma
  *
  * RETURNS:
- * 0 on success, -EINVAL if custom degamma curve is given.
+ * 0 on success
+ * -EINVAL if crtc_state has a degamma_lut of invalid size
+ * -ENOMEM if gamma allocation fails
  */
 int amdgpu_dm_set_degamma_lut(struct drm_crtc_state *crtc_state,
 			      struct dc_plane_state *dc_plane_state)
 {
 	struct drm_property_blob *blob = crtc_state->degamma_lut;
 	struct drm_color_lut *lut;
+	uint32_t lut_size;
+	struct dc_gamma *gamma;
+	bool ret;
 
 	if (!blob) {
 		/* Default to SRGB */
@@ -258,11 +261,30 @@ int amdgpu_dm_set_degamma_lut(struct drm_crtc_state *crtc_state,
 		return 0;
 	}
 
-	/* Otherwise, assume SRGB, since programmable degamma is not
-	 * supported.
-	 */
-	dc_plane_state->in_transfer_func->type = TF_TYPE_PREDEFINED;
-	dc_plane_state->in_transfer_func->tf = TRANSFER_FUNCTION_SRGB;
+	gamma = dc_create_gamma();
+	if (!gamma)
+		return -ENOMEM;
+
+	lut_size = blob->length / sizeof(struct drm_color_lut);
+	gamma->num_entries = lut_size;
+	if (gamma->num_entries == MAX_COLOR_LUT_ENTRIES)
+		gamma->type = GAMMA_CUSTOM;
+	else {
+		dc_gamma_release(&gamma);
 		return -EINVAL;
+	}
+
+	__drm_lut_to_dc_gamma(lut, gamma, false);
+
+	dc_plane_state->in_transfer_func->type = TF_TYPE_DISTRIBUTED_POINTS;
+	ret = mod_color_calculate_degamma_params(dc_plane_state->in_transfer_func, gamma, true);
+	dc_gamma_release(&gamma);
+	if (!ret) {
+		dc_plane_state->in_transfer_func->type = TF_TYPE_BYPASS;
+		DRM_ERROR("Out of memory when calculating degamma params\n");
+		return -ENOMEM;
+	}
+
+	return 0;
 }
 

drivers/gpu/drm/amd/display/dc/dc_hw_types.h

@@ -417,6 +417,7 @@ enum {
 	GAMMA_RGB_256_ENTRIES = 256,
 	GAMMA_RGB_FLOAT_1024_ENTRIES = 1024,
 	GAMMA_CS_TFM_1D_ENTRIES = 4096,
+	GAMMA_CUSTOM_ENTRIES = 4096,
 	GAMMA_MAX_ENTRIES = 4096
 };
 
@@ -424,6 +425,7 @@ enum dc_gamma_type {
 	GAMMA_RGB_256 = 1,
 	GAMMA_RGB_FLOAT_1024 = 2,
 	GAMMA_CS_TFM_1D = 3,
+	GAMMA_CUSTOM = 4,
 };
 
 struct dc_csc_transform {

drivers/gpu/drm/amd/display/dc/dcn10/dcn10_hw_sequencer.c

@@ -1213,8 +1213,11 @@ static bool dcn10_set_input_transfer_func(struct pipe_ctx *pipe_ctx,
 	} else if (tf->type == TF_TYPE_BYPASS) {
 		dpp_base->funcs->dpp_set_degamma(dpp_base, IPP_DEGAMMA_MODE_BYPASS);
 	} else {
-		/*TF_TYPE_DISTRIBUTED_POINTS*/
-		result = false;
+		cm_helper_translate_curve_to_degamma_hw_format(tf,
+					&dpp_base->degamma_params);
+		dpp_base->funcs->dpp_program_degamma_pwl(dpp_base,
+				&dpp_base->degamma_params);
+		result = true;
 	}
 
 	return result;

drivers/gpu/drm/amd/display/modules/color/color_gamma.c

@@ -997,7 +997,9 @@ static void scale_user_regamma_ramp(struct pwl_float_data *pwl_rgb,
  * norm_y = 4095*regamma_y, and index is just truncating to nearest integer
  * lut1 = lut1D[index], lut2 = lut1D[index+1]
  *
- *adjustedY is then linearly interpolating regamma Y between lut1 and lut2
+ * adjustedY is then linearly interpolating regamma Y between lut1 and lut2
+ *
+ * Custom degamma on Linux uses the same interpolation math, so is handled here
  */
 static void apply_lut_1d(
 		const struct dc_gamma *ramp,
@@ -1018,7 +1020,7 @@ static void apply_lut_1d(
 	struct fixed31_32 delta_lut;
 	struct fixed31_32 delta_index;
 
-	if (ramp->type != GAMMA_CS_TFM_1D)
+	if (ramp->type != GAMMA_CS_TFM_1D && ramp->type != GAMMA_CUSTOM)
 		return; // this is not expected
 
 	for (i = 0; i < num_hw_points; i++) {
@@ -1636,7 +1638,9 @@ bool mod_color_calculate_degamma_params(struct dc_transfer_func *input_tf,
 	map_regamma_hw_to_x_user(ramp, coeff, rgb_user,
 			coordinates_x, axix_x, curve,
 			MAX_HW_POINTS, tf_pts,
-			mapUserRamp);
+			mapUserRamp && ramp->type != GAMMA_CUSTOM);
+	if (ramp->type == GAMMA_CUSTOM)
+		apply_lut_1d(ramp, MAX_HW_POINTS, tf_pts);
 
 	ret = true;