[Intel-gfx] [PATCH 21/22] drm/i915: BDW: Pipe level degamma correction

[Shashank Sharma]

BDW/SKL/BXT supports Degamma color correction feature, which
linearizes the non-linearity due to gamma encoded color values.
This will be applied before Color Transformation.

This patch does the following:
1. Adds the core function to program DeGamma correction values for
   BDW/SKL/BXT platform
2. Adds DeGamma correction macros/defines

Signed-off-by: Shashank Sharma <shashank.sharma at intel.com>
Signed-off-by: Kausal Malladi <kausalmalladi at gmail.com>
---
 drivers/gpu/drm/i915/intel_color_manager.c | 59 ++++++++++++++++++++++++++++++
 1 file changed, 59 insertions(+)

diff --git a/drivers/gpu/drm/i915/intel_color_manager.c b/drivers/gpu/drm/i915/intel_color_manager.c
index 74f8fc3..e659382 100644
--- a/drivers/gpu/drm/i915/intel_color_manager.c
+++ b/drivers/gpu/drm/i915/intel_color_manager.c
@@ -273,6 +273,63 @@ static int bdw_set_gamma(struct drm_device *dev, struct drm_property_blob *blob,
 	return 0;
 }
 
+static int bdw_set_degamma(struct drm_device *dev,
+	struct drm_property_blob *blob, struct drm_crtc *crtc)
+{
+	enum pipe pipe;
+	int num_samples, length;
+	u32 index, mode;
+	u32 pal_prec_index, pal_prec_data;
+	struct drm_palette *degamma_data;
+	struct drm_crtc_state *state = crtc->state;
+	struct drm_i915_private *dev_priv = dev->dev_private;
+	struct drm_r32g32b32 *correction_values = NULL;
+
+	if (WARN_ON(!blob))
+		return -EINVAL;
+
+	degamma_data = (struct drm_palette *)blob->data;
+	pipe = to_intel_crtc(crtc)->pipe;
+	num_samples = degamma_data->num_samples;
+
+	if (num_samples == GAMMA_DISABLE_VALS) {
+		/* Disable degamma on Pipe */
+		mode = I915_READ(GAMMA_MODE(pipe)) & ~GAMMA_MODE_MODE_MASK;
+		I915_WRITE(GAMMA_MODE(pipe), mode | GAMMA_MODE_MODE_8BIT);
+
+		state->palette_before_ctm_blob = NULL;
+		DRM_DEBUG_DRIVER("Disabling degamma on Pipe %c\n",
+		pipe_name(pipe));
+		return 0;
+	}
+
+	if (num_samples != BDW_SPLITGAMMA_MAX_VALS) {
+		DRM_ERROR("Invalid number of samples\n");
+		return -EINVAL;
+	}
+
+	length = num_samples * sizeof(struct drm_r32g32b32);
+	mode = I915_READ(GAMMA_MODE(pipe));
+	pal_prec_index = _PREC_PAL_INDEX(pipe);
+	pal_prec_data = _PREC_PAL_DATA(pipe);
+
+	correction_values = (struct drm_r32g32b32 *)&degamma_data->lut;
+	index = I915_READ(pal_prec_index);
+	index |= BDW_INDEX_AUTO_INCREMENT | BDW_INDEX_SPLIT_MODE;
+	I915_WRITE(pal_prec_index, index);
+
+	bdw_write_10bit_gamma_precision(dev, correction_values,
+		pal_prec_data, BDW_SPLITGAMMA_MAX_VALS);
+
+	/* Enable DeGamma on Pipe */
+	mode &= ~GAMMA_MODE_MODE_MASK;
+	I915_WRITE(GAMMA_MODE(pipe), mode | GAMMA_MODE_MODE_SPLIT);
+	DRM_DEBUG_DRIVER("DeGamma correction enabled on Pipe %c\n",
+	pipe_name(pipe));
+
+	return 0;
+}
+
 static s16 chv_prepare_csc_coeff(s64 csc_value)
 {
 	s32 csc_int_value;
@@ -579,6 +636,8 @@ void intel_color_manager_crtc_commit(struct drm_device *dev,
 		/* Degamma correction */
 		if (IS_CHERRYVIEW(dev))
 			ret = chv_set_degamma(dev, blob, crtc);
+		else if (IS_BROADWELL(dev) || IS_GEN9(dev))
+			ret = bdw_set_degamma(dev, blob, crtc);
 
 		if (ret)
 			DRM_ERROR("set degamma correction failed\n");
-- 
1.9.1