[PATCH v6 14/23] drm/i915: CHV: Pipe level degamma correction

[Shashank Sharma]

CHV/BSW supports Degamma color correction, which linearizes all
the non-linear color values. This will be applied before Color
Transformation.

This patch does the following:
1. Attach deGamma property to CRTC
2. Add the core function to program DeGamma correction values for
   CHV/BSW platform
2. Add 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/i915_reg.h            |  6 ++
 drivers/gpu/drm/i915/intel_color_manager.c | 92 ++++++++++++++++++++++++++++++
 drivers/gpu/drm/i915/intel_color_manager.h |  5 ++
 3 files changed, 103 insertions(+)

diff --git a/drivers/gpu/drm/i915/i915_reg.h b/drivers/gpu/drm/i915/i915_reg.h
index 45ddd84..1e46562 100644
--- a/drivers/gpu/drm/i915/i915_reg.h
+++ b/drivers/gpu/drm/i915/i915_reg.h
@@ -8160,4 +8160,10 @@ enum skl_disp_power_wells {
 #define _PIPE_GAMMA_BASE(pipe) \
 	(_PIPE3(pipe, PIPEA_CGM_GAMMA, PIPEB_CGM_GAMMA, PIPEC_CGM_GAMMA))
 
+#define PIPEA_CGM_DEGAMMA                      (VLV_DISPLAY_BASE + 0x66000)
+#define PIPEB_CGM_DEGAMMA                      (VLV_DISPLAY_BASE + 0x68000)
+#define PIPEC_CGM_DEGAMMA                      (VLV_DISPLAY_BASE + 0x6A000)
+#define _PIPE_DEGAMMA_BASE(pipe) \
+	(_PIPE3(pipe, PIPEA_CGM_DEGAMMA, PIPEB_CGM_DEGAMMA, PIPEC_CGM_DEGAMMA))
+
 #endif /* _I915_REG_H_ */
diff --git a/drivers/gpu/drm/i915/intel_color_manager.c b/drivers/gpu/drm/i915/intel_color_manager.c
index acb9647..1bbad79 100644
--- a/drivers/gpu/drm/i915/intel_color_manager.c
+++ b/drivers/gpu/drm/i915/intel_color_manager.c
@@ -27,6 +27,92 @@
 
 #include "intel_color_manager.h"
 
+static int chv_set_degamma(struct drm_device *dev,
+	struct drm_property_blob *blob, struct drm_crtc *crtc)
+{
+	u16 red_fract, green_fract, blue_fract;
+	u32 red, green, blue;
+	u32 num_samples;
+	u32 word = 0;
+	u32 count, cgm_control_reg, cgm_degamma_reg;
+	enum pipe pipe;
+	struct drm_palette *degamma_data;
+	struct drm_i915_private *dev_priv = dev->dev_private;
+	struct drm_r32g32b32 *correction_values = NULL;
+	struct drm_crtc_state *state = crtc->state;
+
+	if (WARN_ON(!blob))
+		return -EINVAL;
+
+	degamma_data = (struct drm_palette *)blob->data;
+	pipe = to_intel_crtc(crtc)->pipe;
+	num_samples = blob->length / sizeof(struct drm_r32g32b32);
+
+	switch (num_samples) {
+	case GAMMA_DISABLE_VALS:
+		/* Disable DeGamma functionality on Pipe - CGM Block */
+		cgm_control_reg = I915_READ(_PIPE_CGM_CONTROL(pipe));
+		cgm_control_reg &= ~CGM_DEGAMMA_EN;
+		state->palette_before_ctm_blob = NULL;
+
+		I915_WRITE(_PIPE_CGM_CONTROL(pipe), cgm_control_reg);
+		DRM_DEBUG_DRIVER("DeGamma disabled on Pipe %c\n",
+				pipe_name(pipe));
+		break;
+
+	case CHV_DEGAMMA_MAX_VALS:
+		cgm_degamma_reg = _PIPE_DEGAMMA_BASE(pipe);
+		count = 0;
+		correction_values = (struct drm_r32g32b32 *)&degamma_data->lut;
+		while (count < CHV_DEGAMMA_MAX_VALS) {
+			blue = correction_values[count].b32;
+			green = correction_values[count].g32;
+			red = correction_values[count].r32;
+
+			if (blue > CHV_MAX_GAMMA)
+				blue = CHV_MAX_GAMMA;
+
+			if (green > CHV_MAX_GAMMA)
+				green = CHV_MAX_GAMMA;
+
+			if (red > CHV_MAX_GAMMA)
+				red = CHV_MAX_GAMMA;
+
+			blue_fract = GET_BITS(blue, 8, 14);
+			green_fract = GET_BITS(green, 8, 14);
+			red_fract = GET_BITS(red, 8, 14);
+
+			/* Green (29:16) and Blue (13:0) in DWORD1 */
+			SET_BITS(word, green_fract, 16, 14);
+			SET_BITS(word, green_fract, 0, 14);
+			I915_WRITE(cgm_degamma_reg, word);
+			cgm_degamma_reg += 4;
+
+			/* Red (13:0) to be written to DWORD2 */
+			word = red_fract;
+			I915_WRITE(cgm_degamma_reg, word);
+			cgm_degamma_reg += 4;
+			count++;
+		}
+
+		DRM_DEBUG_DRIVER("DeGamma LUT loaded for Pipe %c\n",
+				pipe_name(pipe));
+
+		/* Enable DeGamma on Pipe */
+		I915_WRITE(_PIPE_CGM_CONTROL(pipe),
+			I915_READ(_PIPE_CGM_CONTROL(pipe)) | CGM_DEGAMMA_EN);
+
+		DRM_DEBUG_DRIVER("DeGamma correction enabled on Pipe %c\n",
+				pipe_name(pipe));
+		break;
+
+	default:
+		DRM_ERROR("Invalid number of samples for DeGamma LUT\n");
+		return -EINVAL;
+	}
+	return 0;
+}
+
 static int chv_set_gamma(struct drm_device *dev, struct drm_property_blob *blob,
 		struct drm_crtc *crtc)
 {
@@ -155,4 +241,10 @@ void intel_attach_color_properties_to_crtc(struct drm_device *dev,
 		DRM_DEBUG_DRIVER("gamma property attached to CRTC\n");
 	}
 
+	/* Degamma correction */
+	if (config->cm_palette_before_ctm_property) {
+		drm_object_attach_property(mode_obj,
+			config->cm_palette_before_ctm_property, 0);
+		DRM_DEBUG_DRIVER("degamma property attached to CRTC\n");
+	}
 }
diff --git a/drivers/gpu/drm/i915/intel_color_manager.h b/drivers/gpu/drm/i915/intel_color_manager.h
index de706d9..77a2119 100644
--- a/drivers/gpu/drm/i915/intel_color_manager.h
+++ b/drivers/gpu/drm/i915/intel_color_manager.h
@@ -63,5 +63,10 @@
 #define CHV_GAMMA_SHIFT_GREEN                  16
 #define CHV_MAX_GAMMA                          ((1 << 24) - 1)
 
+/* Degamma on CHV */
+#define CHV_DEGAMMA_MSB_SHIFT                  2
+#define CHV_DEGAMMA_GREEN_SHIFT                16
+
 /* CHV CGM Block */
 #define CGM_GAMMA_EN                           (1 << 2)
+#define CGM_DEGAMMA_EN                         (1 << 0)
-- 
1.9.1