drm/i915/xelpd: Enable Pipe Degamma

Enable Pipe Degamma for XE_LPD. Extend the legacy implementation
to incorparate the extended lut size for XE_LPD.

v2: Added a helper for degamma lut size (Ville)
Signed-off-by: Uma Shankar <uma.shankar@intel.com>
Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20211207071135.3660332-3-uma.shankar@intel.com

drivers/gpu/drm/i915/display/intel_color.c

@@ -808,6 +808,14 @@ static void bdw_load_luts(const struct intel_crtc_state *crtc_state)
 	}
 }
 
+static int glk_degamma_lut_size(struct drm_i915_private *i915)
+{
+	if (DISPLAY_VER(i915) >= 13)
+		return 131;
+	else
+		return 35;
+}
+
 static void glk_load_degamma_lut(const struct intel_crtc_state *crtc_state)
 {
 	struct intel_crtc *crtc = to_intel_crtc(crtc_state->uapi.crtc);
@@ -827,8 +835,8 @@ static void glk_load_degamma_lut(const struct intel_crtc_state *crtc_state)
 
 	for (i = 0; i < lut_size; i++) {
 		/*
-		 * First 33 entries represent range from 0 to 1.0
-		 * 34th and 35th entry will represent extended range
+		 * First lut_size entries represent range from 0 to 1.0
+		 * 3 additional lut entries will represent extended range
 		 * inputs 3.0 and 7.0 respectively, currently clamped
 		 * at 1.0. Since the precision is 16bit, the user
 		 * value can be directly filled to register.
@@ -844,7 +852,7 @@ static void glk_load_degamma_lut(const struct intel_crtc_state *crtc_state)
 	}
 
 	/* Clamp values > 1.0. */
-	while (i++ < 35)
+	while (i++ < glk_degamma_lut_size(dev_priv))
 		intel_de_write_fw(dev_priv, PRE_CSC_GAMC_DATA(pipe), 1 << 16);
 
 	intel_de_write_fw(dev_priv, PRE_CSC_GAMC_INDEX(pipe), 0);