media: staging: rkisp1: rsz: remove redundant if statement and add inline doc

The statement "if (rsz->fmt_type == V4L2_PIXEL_ENC_YUV)"
can be removed since the value of rsz->fmt_type is either
V4L2_PIXEL_ENC_YUV or V4L2_PIXEL_ENC_BAYER and the function
returns if it is bayer. In addition some doc with clarification
is added.
Signed-off-by: Dafna Hirschfeld <dafna.hirschfeld@collabora.com>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>

drivers/staging/media/rkisp1/rkisp1-resizer.c

@@ -365,12 +365,17 @@ static void rkisp1_rsz_config(struct rkisp1_resizer *rsz,
 	struct v4l2_rect sink_y, sink_c, src_y, src_c;
 	struct v4l2_mbus_framefmt *src_fmt;
 	struct v4l2_rect *sink_crop;
+	struct rkisp1_capture *cap = &rsz->rkisp1->capture_devs[rsz->id];
 
 	sink_crop = rkisp1_rsz_get_pad_crop(rsz, NULL, RKISP1_RSZ_PAD_SINK,
 					    V4L2_SUBDEV_FORMAT_ACTIVE);
 	src_fmt = rkisp1_rsz_get_pad_fmt(rsz, NULL, RKISP1_RSZ_PAD_SRC,
 					 V4L2_SUBDEV_FORMAT_ACTIVE);
 
+	/*
+	 * The resizer only works on yuv formats,
+	 * so return if it is bayer format.
+	 */
 	if (rsz->pixel_enc == V4L2_PIXEL_ENC_BAYER) {
 		rkisp1_rsz_disable(rsz, when);
 		return;
@@ -384,13 +389,15 @@ static void rkisp1_rsz_config(struct rkisp1_resizer *rsz,
 	sink_c.width = sink_y.width / RKISP1_MBUS_FMT_HDIV;
 	sink_c.height = sink_y.height / RKISP1_MBUS_FMT_VDIV;
 
-	if (rsz->pixel_enc == V4L2_PIXEL_ENC_YUV) {
-		struct rkisp1_capture *cap =
-			&rsz->rkisp1->capture_devs[rsz->id];
+	/*
+	 * The resizer is used not only to change the dimensions of the frame
+	 * but also to change the scale for YUV formats,
+	 * (4:2:2 -> 4:2:0 for example). So the width/height of the CbCr
+	 * streams should be set according to the pixel format in the capture.
+	 */
+	hdiv = cap->pix.info->hdiv;
+	vdiv = cap->pix.info->vdiv;
 
-		hdiv = cap->pix.info->hdiv;
-		vdiv = cap->pix.info->vdiv;
-	}
 	src_c.width = src_y.width / hdiv;
 	src_c.height = src_y.height / vdiv;