[RFC PATCH 18/40] drm/amd/display: encapsulate atomic regamma operation

[Melissa Wen]

We are introducing DRM 3D LUT property to DM color pipeline in the next
patch, but so far, only for atomic interface. By checking
set_output_transfer_func in DC drivers with MPC 3D LUT support, we can
verify that regamma is only programmed when 3D LUT programming fails. As
a groundwork to introduce 3D LUT programming and better understand each
step, detach atomic regamma programming from the crtc colocr updating
code.

Signed-off-by: Melissa Wen <mwen at igalia.com>
---
 .../amd/display/amdgpu_dm/amdgpu_dm_color.c   | 52 ++++++++++++-------
 1 file changed, 33 insertions(+), 19 deletions(-)

diff --git a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_color.c b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_color.c
index fe779d10834e..f1885e9c614d 100644
--- a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_color.c
+++ b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_color.c
@@ -303,6 +303,35 @@ static int __set_output_tf(struct dc_transfer_func *func,
 	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)
+{
+	int ret = 0;
+	if (regamma_size) {
+		/* 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.
+		 */
+		stream->out_transfer_func->type = TF_TYPE_DISTRIBUTED_POINTS;
+		stream->out_transfer_func->tf = TRANSFER_FUNCTION_LINEAR;
+
+		ret = __set_output_tf(stream->out_transfer_func,
+				      regamma_lut, regamma_size, has_rom);
+	} else {
+		/*
+		 * No CRTC RGM means we can just put the block into bypass
+		 * since we don't have any plane level adjustments using it.
+		 */
+		stream->out_transfer_func->type = TF_TYPE_BYPASS;
+		stream->out_transfer_func->tf = TRANSFER_FUNCTION_LINEAR;
+	}
+
+	return ret;
+}
+
 /**
  * __set_input_tf - calculates the input transfer function based on expected
  * input space.
@@ -450,27 +479,12 @@ int amdgpu_dm_update_crtc_color_mgmt(struct dm_crtc_state *crtc)
 				    regamma_size, has_rom);
 		if (r)
 			return r;
-	} else if (has_regamma) {
-		/* 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.
-		 */
-		stream->out_transfer_func->type = TF_TYPE_DISTRIBUTED_POINTS;
-		stream->out_transfer_func->tf = TRANSFER_FUNCTION_LINEAR;
-
-		r = __set_output_tf(stream->out_transfer_func, regamma_lut,
-				    regamma_size, has_rom);
+	} else {
+		regamma_size = has_regamma ? regamma_size : 0;
+		r = amdgpu_dm_set_atomic_regamma(stream, regamma_lut,
+						 regamma_size, has_rom);
 		if (r)
 			return r;
-	} else {
-		/*
-		 * No CRTC RGM means we can just put the block into bypass
-		 * since we don't have any plane level adjustments using it.
-		 */
-		stream->out_transfer_func->type = TF_TYPE_BYPASS;
-		stream->out_transfer_func->tf = TRANSFER_FUNCTION_LINEAR;
 	}
 
 	/*
-- 
2.39.2