drm/amd/display: add plane 3D LUT driver-specific properties

Add 3D LUT property for plane color transformations using a 3D lookup
table. 3D LUT allows for highly accurate and complex color
transformations and is suitable to adjust the balance between color
channels. It's also more complex to manage and require more
computational resources.

Since a 3D LUT has a limited number of entries in each dimension we want
to use them in an optimal fashion. This means using the 3D LUT in a
colorspace that is optimized for human vision, such as sRGB, PQ, or
another non-linear space. Therefore, userpace may need one 1D LUT
(shaper) before it to delinearize content and another 1D LUT after 3D
LUT (blend) to linearize content again for blending. The next patches
add these 1D LUTs to the plane color mgmt pipeline.

v3:
- improve commit message about 3D LUT
- describe the 3D LUT entries and size (Harry)

v4:
- advertise 3D LUT max size as the size of a single-dimension

v5:
- get lut3d blob correctly (Joshua)
- fix doc about 3d-lut dimension size (Sebastian)

Signed-off-by: Melissa Wen <mwen@igalia.com>
Reviewed-by: Harry Wentland <harry.wentland@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

1 files changed, 18 insertions, 0 deletions

diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_mode.h b/drivers/gpu/drm/amd/amdgpu/amdgpu_mode.h
index 218623e1b9aa..7350094f3db6 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_mode.h
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_mode.h
@@ -364,6 +364,24 @@ struct amdgpu_mode_info {
 	 * @plane_hdr_mult_property:
 	 */
 	struct drm_property *plane_hdr_mult_property;
+	/**
+	 * @plane_lut3d_property: Plane property for color transformation using
+	 * a 3D LUT (pre-blending), a three-dimensional array where each
+	 * element is an RGB triplet. Each dimension has the size of
+	 * lut3d_size. The array contains samples from the approximated
+	 * function. On AMD, values between samples are estimated by
+	 * tetrahedral interpolation. The array is accessed with three indices,
+	 * one for each input dimension (color channel), blue being the
+	 * outermost dimension, red the innermost.
+	 */
+	struct drm_property *plane_lut3d_property;
+	/**
+	 * @plane_degamma_lut_size_property: Plane property to define the max
+	 * size of 3D LUT as supported by the driver (read-only). The max size
+	 * is the max size of one dimension and, therefore, the max number of
+	 * entries for 3D LUT array is the 3D LUT size cubed;
+	 */
+	struct drm_property *plane_lut3d_size_property;
 };
 
 #define AMDGPU_MAX_BL_LEVEL 0xFF