drm/amd/display: add CRTC gamma TF driver-specific property

Add AMD pre-defined transfer function property to default DRM CRTC gamma
to convert to wire encoding with or without a user gamma LUT. There is
no post-blending regamma ROM for pre-defined TF. When setting Gamma TF
(!= Identity) and LUT at the same time, the color module will combine
the pre-defined TF and the custom LUT values into the LUT that's
actually programmed.

v2:
- enable CRTC prop in the end of driver-specific prop sequence
- define inverse EOTFs as supported regamma TFs
- reword driver-specific function doc to remove shaper/3D LUT

v3:
- spell out TF+LUT behavior in the commit and comments (Harry)

Reviewed-by: Harry Wentland <[email protected]>
Co-developed-by: Joshua Ashton <[email protected]>
Signed-off-by: Joshua Ashton <[email protected]>
Signed-off-by: Melissa Wen <[email protected]>
Signed-off-by: Alex Deucher <[email protected]>

1 files changed, 7 insertions, 0 deletions

diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_mode.h b/drivers/gpu/drm/amd/amdgpu/amdgpu_mode.h
index 6ff37272ccad..9fbe09743dde 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_mode.h
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_mode.h
@@ -425,6 +425,13 @@ struct amdgpu_mode_info {
 	 * from a combination of pre-defined TF and the custom 1D LUT).
 	 */
 	struct drm_property *plane_blend_tf_property;
+	/* @regamma_tf_property: Transfer function for CRTC regamma
+	 * (post-blending). Possible values are defined by `enum
+	 * amdgpu_transfer_function`. There is no regamma ROM, but we can use
+	 * AMD color modules to program LUT parameters from predefined TF (or
+	 * from a combination of pre-defined TF and the custom 1D LUT).
+	 */
+	struct drm_property *regamma_tf_property;
 };
 
 #define AMDGPU_MAX_BL_LEVEL 0xFF