drm/amd/display: add CRTC gamma TF support

Add predefined transfer function programming. There is no post-blending
out gamma ROM for hardcoded curves, but we can use AMD color modules to
program LUT parameters from pre-defined coefficients and an empty
regamma LUT (or bump up LUT parameters with pre-defined TF values).

v2:
- update crtc color mgmt if regamma TF differs between states (Joshua)
- map inverse EOTF to DC transfer function (Melissa)

v3:
- update AMDGPU TF list

v4:
- update comment regarding regamma behavior
Reviewed-by: Harry Wentland <harry.wentland@amd.com>
Signed-off-by: Joshua Ashton <joshua@froggi.es>
Co-developed-by: Melissa Wen <mwen@igalia.com>
Signed-off-by: Melissa Wen <mwen@igalia.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

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

@@ -9860,6 +9860,7 @@ static int dm_update_crtc_state(struct amdgpu_display_manager *dm,
 	 * when a modeset is needed, to ensure it gets reprogrammed.
 	 */
 	if (dm_new_crtc_state->base.color_mgmt_changed ||
+	    dm_old_crtc_state->regamma_tf != dm_new_crtc_state->regamma_tf ||
 	    drm_atomic_crtc_needs_modeset(new_crtc_state)) {
 		ret = amdgpu_dm_update_crtc_color_mgmt(dm_new_crtc_state);
 		if (ret)

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

@@ -490,16 +490,18 @@ static int __set_output_tf(struct dc_transfer_func *func,
 	struct calculate_buffer cal_buffer = {0};
 	bool res;
 
-	ASSERT(lut && lut_size == MAX_COLOR_LUT_ENTRIES);
-
 	cal_buffer.buffer_index = -1;
 
-	gamma = dc_create_gamma();
-	if (!gamma)
-		return -ENOMEM;
+	if (lut_size) {
+		ASSERT(lut && lut_size == MAX_COLOR_LUT_ENTRIES);
 
-	gamma->num_entries = lut_size;
-	__drm_lut_to_dc_gamma(lut, gamma, false);
+		gamma = dc_create_gamma();
+		if (!gamma)
+			return -ENOMEM;
+
+		gamma->num_entries = lut_size;
+		__drm_lut_to_dc_gamma(lut, gamma, false);
+	}
 
 	if (func->tf == TRANSFER_FUNCTION_LINEAR) {
 		/*
@@ -507,41 +509,49 @@ static int __set_output_tf(struct dc_transfer_func *func,
 		 * on top of a linear input. But degamma params can be used
 		 * instead to simulate this.
 		 */
-		gamma->type = GAMMA_CUSTOM;
+		if (gamma)
+			gamma->type = GAMMA_CUSTOM;
 		res = mod_color_calculate_degamma_params(NULL, func,
-							gamma, true);
+							 gamma, gamma != NULL);
 	} else {
 		/*
 		 * Assume sRGB. The actual mapping will depend on whether the
 		 * input was legacy or not.
 		 */
-		gamma->type = GAMMA_CS_TFM_1D;
-		res = mod_color_calculate_regamma_params(func, gamma, false,
+		if (gamma)
+			gamma->type = GAMMA_CS_TFM_1D;
+		res = mod_color_calculate_regamma_params(func, gamma, gamma != NULL,
 							 has_rom, NULL, &cal_buffer);
 	}
 
-	dc_gamma_release(&gamma);
+	if (gamma)
+		dc_gamma_release(&gamma);
 
 	return res ? 0 : -ENOMEM;
 }
 
 static int amdgpu_dm_set_atomic_regamma(struct dc_stream_state *stream,
 					const struct drm_color_lut *regamma_lut,
-					uint32_t regamma_size, bool has_rom)
+					uint32_t regamma_size, bool has_rom,
+					enum dc_transfer_func_predefined tf)
 {
 	struct dc_transfer_func *out_tf = stream->out_transfer_func;
 	int ret = 0;
 
-	if (regamma_size) {
+	if (regamma_size || tf != TRANSFER_FUNCTION_LINEAR) {
 		/*
 		 * CRTC RGM goes into RGM LUT.
 		 *
 		 * Note: there is no implicit sRGB regamma here. We are using
 		 * degamma calculation from color module to calculate the curve
-		 * from a linear base.
+		 * from a linear base if gamma TF is not set. However, if gamma
+		 * TF (!= Linear) and LUT are set at the same time, we will use
+		 * regamma calculation, and the color module will combine the
+		 * pre-defined TF and the custom LUT values into the LUT that's
+		 * actually programmed.
 		 */
 		out_tf->type = TF_TYPE_DISTRIBUTED_POINTS;
-		out_tf->tf = TRANSFER_FUNCTION_LINEAR;
+		out_tf->tf = tf;
 
 		ret = __set_output_tf(out_tf, regamma_lut, regamma_size, has_rom);
 	} else {
@@ -587,6 +597,36 @@ static int __set_input_tf(struct dc_transfer_func *func,
 	return res ? 0 : -ENOMEM;
 }
 
+static enum dc_transfer_func_predefined
+amdgpu_tf_to_dc_tf(enum amdgpu_transfer_function tf)
+{
+	switch (tf)
+	{
+	default:
+	case AMDGPU_TRANSFER_FUNCTION_DEFAULT:
+	case AMDGPU_TRANSFER_FUNCTION_IDENTITY:
+		return TRANSFER_FUNCTION_LINEAR;
+	case AMDGPU_TRANSFER_FUNCTION_SRGB_EOTF:
+	case AMDGPU_TRANSFER_FUNCTION_SRGB_INV_EOTF:
+		return TRANSFER_FUNCTION_SRGB;
+	case AMDGPU_TRANSFER_FUNCTION_BT709_OETF:
+	case AMDGPU_TRANSFER_FUNCTION_BT709_INV_OETF:
+		return TRANSFER_FUNCTION_BT709;
+	case AMDGPU_TRANSFER_FUNCTION_PQ_EOTF:
+	case AMDGPU_TRANSFER_FUNCTION_PQ_INV_EOTF:
+		return TRANSFER_FUNCTION_PQ;
+	case AMDGPU_TRANSFER_FUNCTION_GAMMA22_EOTF:
+	case AMDGPU_TRANSFER_FUNCTION_GAMMA22_INV_EOTF:
+		return TRANSFER_FUNCTION_GAMMA22;
+	case AMDGPU_TRANSFER_FUNCTION_GAMMA24_EOTF:
+	case AMDGPU_TRANSFER_FUNCTION_GAMMA24_INV_EOTF:
+		return TRANSFER_FUNCTION_GAMMA24;
+	case AMDGPU_TRANSFER_FUNCTION_GAMMA26_EOTF:
+	case AMDGPU_TRANSFER_FUNCTION_GAMMA26_INV_EOTF:
+		return TRANSFER_FUNCTION_GAMMA26;
+	}
+}
+
 /**
  * amdgpu_dm_verify_lut_sizes - verifies if DRM luts match the hw supported sizes
  * @crtc_state: the DRM CRTC state
@@ -654,9 +694,12 @@ int amdgpu_dm_update_crtc_color_mgmt(struct dm_crtc_state *crtc)
 	const struct drm_color_lut *degamma_lut, *regamma_lut;
 	uint32_t degamma_size, regamma_size;
 	bool has_regamma, has_degamma;
+	enum dc_transfer_func_predefined tf = TRANSFER_FUNCTION_LINEAR;
 	bool is_legacy;
 	int r;
 
+	tf = amdgpu_tf_to_dc_tf(crtc->regamma_tf);
+
 	r = amdgpu_dm_verify_lut_sizes(&crtc->base);
 	if (r)
 		return r;
@@ -706,7 +749,7 @@ int amdgpu_dm_update_crtc_color_mgmt(struct dm_crtc_state *crtc)
 	} else {
 		regamma_size = has_regamma ? regamma_size : 0;
 		r = amdgpu_dm_set_atomic_regamma(stream, regamma_lut,
-						 regamma_size, has_rom);
+						 regamma_size, has_rom, tf);
 		if (r)
 			return r;
 	}