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.sha...@intel.com>
Signed-off-by: Kausal Malladi <kausalmall...@gmail.com>
---
 drivers/gpu/drm/i915/i915_reg.h            |   6 ++
 drivers/gpu/drm/i915/intel_color_manager.c | 111 +++++++++++++++++++++++++++++
 drivers/gpu/drm/i915/intel_color_manager.h |   6 ++
 3 files changed, 123 insertions(+)

diff --git a/drivers/gpu/drm/i915/i915_reg.h b/drivers/gpu/drm/i915/i915_reg.h
index 93aa1f9..3dde6a8 100644
--- a/drivers/gpu/drm/i915/i915_reg.h
+++ b/drivers/gpu/drm/i915/i915_reg.h
@@ -7989,4 +7989,10 @@ 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 222924d..e2ffbdc 100644
--- a/drivers/gpu/drm/i915/intel_color_manager.c
+++ b/drivers/gpu/drm/i915/intel_color_manager.c
@@ -66,6 +66,111 @@ int intel_color_manager_set_pipe_degamma(struct drm_device 
*dev,
        return 0;
 }
 
+static int chv_set_degamma(struct drm_device *dev,
+       struct drm_property_blob *blob, struct drm_crtc *crtc)
+{
+       struct drm_palette *degamma_data;
+       struct drm_i915_private *dev_priv = dev->dev_private;
+       u32 cgm_control_reg = 0;
+       u32 cgm_degamma_reg = 0;
+       enum pipe pipe;
+       u32 red, green, blue;
+       u8 red_int, green_int, blue_int;
+       u16 red_fract, green_fract, blue_fract;
+       u32 count = 0;
+       struct drm_r32g32b32 *correction_values = NULL;
+       u32 num_samples;
+       u32 word;
+       int ret = 0, length;
+
+       if (!blob) {
+               DRM_ERROR("NULL Blob\n");
+               return -EINVAL;
+       }
+
+       degamma_data = (struct drm_palette *)blob->data;
+
+       if (degamma_data->version != DEGAMMA_DATA_STRUCT_VERSION) {
+               DRM_ERROR("Invalid DeGamma Data struct version\n");
+               return -EINVAL;
+       }
+
+       pipe = to_intel_crtc(crtc)->pipe;
+       num_samples = degamma_data->num_samples;
+       length = num_samples * sizeof(struct drm_r32g32b32);
+
+       if (num_samples == 0) {
+
+               /* Disable DeGamma functionality on Pipe - CGM Block */
+               cgm_control_reg = I915_READ(_PIPE_CGM_CONTROL(pipe));
+               cgm_control_reg &= ~CGM_DEGAMMA_EN;
+               I915_WRITE(_PIPE_CGM_CONTROL(pipe), cgm_control_reg);
+
+               DRM_DEBUG_DRIVER("DeGamma disabled on Pipe %c\n",
+                               pipe_name(pipe));
+               ret = 0;
+       } else if (num_samples == 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;
+
+                       blue_int = _GAMMA_INT_PART(blue);
+                       if (blue_int > GAMMA_INT_MAX)
+                               blue = CHV_MAX_GAMMA;
+                       green_int = _GAMMA_INT_PART(green);
+                       if (green_int > GAMMA_INT_MAX)
+                               green = CHV_MAX_GAMMA;
+                       red_int = _GAMMA_INT_PART(red);
+                       if (red_int > GAMMA_INT_MAX)
+                               red = CHV_MAX_GAMMA;
+
+                       blue_fract = _GAMMA_FRACT_PART(blue);
+                       green_fract = _GAMMA_FRACT_PART(green);
+                       red_fract = _GAMMA_FRACT_PART(red);
+
+                       blue_fract >>= CHV_DEGAMMA_MSB_SHIFT;
+                       green_fract >>= CHV_DEGAMMA_MSB_SHIFT;
+                       red_fract >>= CHV_DEGAMMA_MSB_SHIFT;
+
+                       /* Green (29:16) and Blue (13:0) in DWORD1 */
+                       word = green_fract;
+                       word <<= CHV_DEGAMMA_GREEN_SHIFT;
+                       word = word | blue;
+                       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));
+               ret = 0;
+       } else {
+               DRM_ERROR("Invalid number of samples for DeGamma LUT\n");
+               return -EINVAL;
+       }
+
+       return ret;
+}
+
 static int chv_set_gamma(struct drm_device *dev, struct drm_property_blob 
*blob,
                  struct drm_crtc *crtc)
 {
@@ -261,5 +366,11 @@ void intel_attach_color_properties_to_crtc(struct 
drm_device *dev,
                DRM_DEBUG_DRIVER("palette after CTM attached to CRTC\n");
        }
 
+       if (config->cm_palette_before_ctm_property) {
+               drm_object_attach_property(mode_obj,
+                       config->cm_palette_before_ctm_property, 0);
+               DRM_DEBUG_DRIVER("palette before CTM attached to CRTC\n");
+       }
+
        kfree(palette_caps);
 }
diff --git a/drivers/gpu/drm/i915/intel_color_manager.h 
b/drivers/gpu/drm/i915/intel_color_manager.h
index 5f800c9..5eaa0f3 100644
--- a/drivers/gpu/drm/i915/intel_color_manager.h
+++ b/drivers/gpu/drm/i915/intel_color_manager.h
@@ -50,5 +50,11 @@
 /* Max value for Gamma on CHV */
 #define CHV_MAX_GAMMA                          0x10000
 
+/* DeGamma correction */
+#define DEGAMMA_DATA_STRUCT_VERSION        1
+#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

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