drm/amd/display: Add support for sRGB EOTF in BLND block

Expose a 3rd 1D curve colorop, with support for
DRM_COLOROP_1D_CURVE_SRGB_EOTF and program the BLND block
to perform the sRGB transform when the colorop is not in
bypass

With this change the following IGT test passes:
kms_colorop --run plane-XR30-XR30-srgb_eotf-srgb_inv_eotf-srgb_eotf

The color pipeline now consists of the following colorops:
1. 1D curve colorop w/ sRGB EOTF support
2. 1D curve colorop w/ sRGB Inverse EOTF support
3. 1D curve colorop w/ sRGB EOTF support

Signed-off-by: Alex Hung <alex.hung@amd.com>
Co-developed-by: Harry Wentland <harry.wentland@amd.com>
Signed-off-by: Harry Wentland <harry.wentland@amd.com>
Reviewed-by: Daniel Stone <daniels@collabora.com>
Signed-off-by: Simon Ser <contact@emersion.fr>
Link: https://patch.msgid.link/20251115000237.3561250-31-alex.hung@amd.com

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

@@ -1304,6 +1304,70 @@ __set_dm_plane_colorop_shaper(struct drm_plane_state *plane_state,
 	return __set_colorop_in_shaper_1d_curve(dc_plane_state, colorop_state);
 }
 
+static int
+__set_colorop_1d_curve_blend_tf_lut(struct dc_plane_state *dc_plane_state,
+				    struct drm_colorop_state *colorop_state)
+{
+	struct dc_transfer_func *tf = &dc_plane_state->blend_tf;
+	struct drm_colorop *colorop = colorop_state->colorop;
+	struct drm_device *drm = colorop->dev;
+	const struct drm_color_lut *blend_lut = NULL;
+	u32 blend_size = 0;
+
+	if (colorop->type != DRM_COLOROP_1D_CURVE &&
+	    colorop_state->curve_1d_type != DRM_COLOROP_1D_CURVE_SRGB_EOTF)
+		return -EINVAL;
+
+	if (colorop_state->bypass) {
+		tf->type = TF_TYPE_BYPASS;
+		tf->tf = TRANSFER_FUNCTION_LINEAR;
+		return 0;
+	}
+
+	drm_dbg(drm, "Blend colorop with ID: %d\n", colorop->base.id);
+
+	if (colorop->type == DRM_COLOROP_1D_CURVE) {
+		tf->type = TF_TYPE_DISTRIBUTED_POINTS;
+		tf->tf = amdgpu_colorop_tf_to_dc_tf(colorop_state->curve_1d_type);
+		tf->sdr_ref_white_level = SDR_WHITE_LEVEL_INIT_VALUE;
+		return __set_input_tf(NULL, tf, blend_lut, blend_size);
+	}
+
+	return -EINVAL;
+}
+
+static int
+__set_dm_plane_colorop_blend(struct drm_plane_state *plane_state,
+			     struct dc_plane_state *dc_plane_state,
+			     struct drm_colorop *colorop)
+{
+	struct drm_colorop *old_colorop;
+	struct drm_colorop_state *colorop_state = NULL, *new_colorop_state;
+	struct drm_atomic_state *state = plane_state->state;
+	int i = 0;
+
+	old_colorop = colorop;
+
+	/* 3nd op: 1d curve - blend */
+	for_each_new_colorop_in_state(state, colorop, new_colorop_state, i) {
+		if (new_colorop_state->colorop == old_colorop &&
+		    new_colorop_state->curve_1d_type == DRM_COLOROP_1D_CURVE_SRGB_EOTF) {
+			colorop_state = new_colorop_state;
+			break;
+		}
+
+		if (new_colorop_state->colorop == old_colorop) {
+			colorop_state = new_colorop_state;
+			break;
+		}
+	}
+
+	if (!colorop_state)
+		return -EINVAL;
+
+	return __set_colorop_1d_curve_blend_tf_lut(dc_plane_state, colorop_state);
+}
+
 static int
 amdgpu_dm_plane_set_color_properties(struct drm_plane_state *plane_state,
 				     struct dc_plane_state *dc_plane_state)
@@ -1381,6 +1445,17 @@ amdgpu_dm_plane_set_colorop_properties(struct drm_plane_state *plane_state,
 	if (ret)
 		return ret;
 
+	/* 1D Curve - BLND TF */
+	colorop = colorop->next;
+	if (!colorop) {
+		drm_dbg(dev, "no Blend TF colorop found\n");
+		return -EINVAL;
+	}
+
+	ret = __set_dm_plane_colorop_blend(plane_state, dc_plane_state, colorop);
+	if (ret)
+		return ret;
+
 	return 0;
 }
 

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

@@ -37,6 +37,9 @@ const u64 amdgpu_dm_supported_degam_tfs =
 const u64 amdgpu_dm_supported_shaper_tfs =
 	BIT(DRM_COLOROP_1D_CURVE_SRGB_INV_EOTF);
 
+const u64 amdgpu_dm_supported_blnd_tfs =
+	BIT(DRM_COLOROP_1D_CURVE_SRGB_EOTF);
+
 #define MAX_COLOR_PIPELINE_OPS 10
 
 int amdgpu_dm_initialize_default_pipeline(struct drm_plane *plane, struct drm_prop_enum_list *list)
@@ -77,6 +80,21 @@ int amdgpu_dm_initialize_default_pipeline(struct drm_plane *plane, struct drm_pr
 
 	drm_colorop_set_next_property(ops[i - 1], ops[i]);
 
+	i++;
+
+	/* 1D curve - BLND TF */
+	ops[i] = kzalloc(sizeof(*ops[0]), GFP_KERNEL);
+	if (!ops[i]) {
+		ret = -ENOMEM;
+		goto cleanup;
+	}
+
+	ret = drm_plane_colorop_curve_1d_init(dev, ops[i], plane, amdgpu_dm_supported_blnd_tfs);
+	if (ret)
+		goto cleanup;
+
+	drm_colorop_set_next_property(ops[i - 1], ops[i]);
+
 	return 0;
 
 cleanup:

drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_colorop.h

@@ -29,6 +29,7 @@
 
 extern const u64 amdgpu_dm_supported_degam_tfs;
 extern const u64 amdgpu_dm_supported_shaper_tfs;
+extern const u64 amdgpu_dm_supported_blnd_tfs;
 
 int amdgpu_dm_initialize_default_pipeline(struct drm_plane *plane, struct drm_prop_enum_list *list);