[PATCH 3/7] drm/vkmm: Use drm_fixed api

[Arthur Grillo <arthurgrillo@xxxxxxxxxx>]

With the new 32.32 values it makes more sense to use drm_fixed functions
than trying to recreate the wheel.

Signed-off-by: Arthur Grillo <arthurgrillo@xxxxxxxxxx>
---
 drivers/gpu/drm/vkms/vkms_formats.c | 54 +++++++++++++++++++------------------
 1 file changed, 28 insertions(+), 26 deletions(-)

diff --git a/drivers/gpu/drm/vkms/vkms_formats.c b/drivers/gpu/drm/vkms/vkms_formats.c
index 55ed3f598bd7..adde53cdea26 100644
--- a/drivers/gpu/drm/vkms/vkms_formats.c
+++ b/drivers/gpu/drm/vkms/vkms_formats.c
@@ -191,32 +191,34 @@ VISIBLE_IF_KUNIT struct pixel_argb_u16 argb_u16_from_yuv888(u8 y, u8 cb, u8 cr,
 						  struct conversion_matrix *matrix)
 {
 	u8 r, g, b;
-	s64 y_16, cb_16, cr_16;
-	s64 r_16, g_16, b_16;
-
-	y_16 = y - matrix->y_offset;
-	cb_16 = cb - 128;
-	cr_16 = cr - 128;
-
-	r_16 = matrix->matrix[0][0] * y_16 + matrix->matrix[0][1] * cb_16 +
-	       matrix->matrix[0][2] * cr_16;
-	g_16 = matrix->matrix[1][0] * y_16 + matrix->matrix[1][1] * cb_16 +
-	       matrix->matrix[1][2] * cr_16;
-	b_16 = matrix->matrix[2][0] * y_16 + matrix->matrix[2][1] * cb_16 +
-	       matrix->matrix[2][2] * cr_16;
-
-	// rounding the values
-	r_16 = r_16 + (1LL << (CONVERSION_MATRIX_FLOAT_DEPTH - 4));
-	g_16 = g_16 + (1LL << (CONVERSION_MATRIX_FLOAT_DEPTH - 4));
-	b_16 = b_16 + (1LL << (CONVERSION_MATRIX_FLOAT_DEPTH - 4));
-
-	r_16 = clamp(r_16, 0, (1LL << (CONVERSION_MATRIX_FLOAT_DEPTH + 8)) - 1);
-	g_16 = clamp(g_16, 0, (1LL << (CONVERSION_MATRIX_FLOAT_DEPTH + 8)) - 1);
-	b_16 = clamp(b_16, 0, (1LL << (CONVERSION_MATRIX_FLOAT_DEPTH + 8)) - 1);
-
-	r = r_16 >> CONVERSION_MATRIX_FLOAT_DEPTH;
-	g = g_16 >> CONVERSION_MATRIX_FLOAT_DEPTH;
-	b = b_16 >> CONVERSION_MATRIX_FLOAT_DEPTH;
+	s64 fp_y, fp_cb, fp_cr;
+	s64 fp_r, fp_g, fp_b;
+
+	fp_y = y - matrix->y_offset;
+	fp_cb = cb - 128;
+	fp_cr = cr - 128;
+
+	fp_y = drm_int2fixp(fp_y);
+	fp_cb = drm_int2fixp(fp_cb);
+	fp_cr = drm_int2fixp(fp_cr);
+
+	fp_r = drm_fixp_mul(matrix->matrix[0][0], fp_y) +
+	       drm_fixp_mul(matrix->matrix[0][1], fp_cb) +
+	       drm_fixp_mul(matrix->matrix[0][2], fp_cr);
+	fp_g = drm_fixp_mul(matrix->matrix[1][0], fp_y) +
+	       drm_fixp_mul(matrix->matrix[1][1], fp_cb) +
+	       drm_fixp_mul(matrix->matrix[1][2], fp_cr);
+	fp_b = drm_fixp_mul(matrix->matrix[2][0], fp_y) +
+	       drm_fixp_mul(matrix->matrix[2][1], fp_cb) +
+	       drm_fixp_mul(matrix->matrix[2][2], fp_cr);
+
+	fp_r = drm_fixp2int_round(fp_r);
+	fp_g = drm_fixp2int_round(fp_g);
+	fp_b = drm_fixp2int_round(fp_b);
+
+	r = clamp(fp_r, 0, 0xff);
+	g = clamp(fp_g, 0, 0xff);
+	b = clamp(fp_b, 0, 0xff);
 
 	return argb_u16_from_u8888(255, r, g, b);
 }

-- 
2.43.0