drm/amd/display: add dc_fixpt_from_s3132 helper

Detach value translation from CTM to reuse it for programming HDR
multiplier property.
Reviewed-by: Harry Wentland <harry.wentland@amd.com>
Signed-off-by: Joshua Ashton <joshua@froggi.es>
Signed-off-by: Melissa Wen <mwen@igalia.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_color.c

@@ -405,7 +405,6 @@ static void __drm_lut_to_dc_gamma(const struct drm_color_lut *lut,
 static void __drm_ctm_to_dc_matrix(const struct drm_color_ctm *ctm,
 				   struct fixed31_32 *matrix)
 {
-	int64_t val;
 	int i;
 
 	/*
@@ -424,12 +423,7 @@ static void __drm_ctm_to_dc_matrix(const struct drm_color_ctm *ctm,
 		}
 
 		/* gamut_remap_matrix[i] = ctm[i - floor(i/4)] */
-		val = ctm->matrix[i - (i / 4)];
-		/* If negative, convert to 2's complement. */
-		if (val & (1ULL << 63))
-			val = -(val & ~(1ULL << 63));
-
-		matrix[i].value = val;
+		matrix[i] = dc_fixpt_from_s3132(ctm->matrix[i - (i / 4)]);
 	}
 }
 

drivers/gpu/drm/amd/display/include/fixed31_32.h

@@ -69,6 +69,18 @@ static const struct fixed31_32 dc_fixpt_epsilon = { 1LL };
 static const struct fixed31_32 dc_fixpt_half = { 0x80000000LL };
 static const struct fixed31_32 dc_fixpt_one = { 0x100000000LL };
 
+static inline struct fixed31_32 dc_fixpt_from_s3132(__u64 x)
+{
+	struct fixed31_32 val;
+
+	/* If negative, convert to 2's complement. */
+	if (x & (1ULL << 63))
+		x = -(x & ~(1ULL << 63));
+
+	val.value = x;
+	return val;
+}
+
 /*
  * @brief
  * Initialization routines