media: Zero-initialize all structures passed to subdev pad operations

Several drivers call subdev pad operations, passing structures that are
not fully zeroed. While the drivers initialize the fields they care
about explicitly, this results in reserved fields having uninitialized
values. Future kernel API changes that make use of those fields thus
risk breaking proper driver operation in ways that could be hard to
detect.

To avoid this, make the code more robust by zero-initializing all the
structures passed to subdev pad operation. Maintain a consistent coding
style by preferring designated initializers (which zero-initialize all
the fields that are not specified) over memset() where possible, and
make variable declarations local to inner scopes where applicable. One
notable exception to this rule is in the ipu3 driver, where a memset()
is needed as the structure is not a local variable but a function
parameter provided by the caller.

Not all fields of those structures can be initialized when declaring the
variables, as the values for those fields are computed later in the
code. Initialize the 'which' field in all cases, and other fields when
the variable declaration is so close to the v4l2_subdev_call() call that
it keeps all the context easily visible when reading the code, to avoid
hindering readability.

Signed-off-by: Laurent Pinchart <[e-mail]>
Acked-by: Shuah Khan <[e-mail]> # For vimc
Reviewed-by: Lad Prabhakar <[e-mail]> # For am437x
Acked-by: Sakari Ailus <[e-mail]>
Reviewed-by: Tomi Valkeinen <[e-mail]>
Reviewed-by: Kieran Bingham <[e-mail]>
Reviewed-by: Philipp Zabel <[e-mail]> # For drivers/staging/media/imx/
Signed-off-by: Hans Verkuil <[e-mail]>

drivers/media/pci/cobalt/cobalt-v4l2.c

···
 {
 	struct cobalt_stream *s = video_drvdata(file);
 	struct v4l2_pix_format *pix = &f->fmt.pix;
-	struct v4l2_subdev_format sd_fmt;
 
 	pix->width = s->width;
 	pix->height = s->height;
···
 	if (s->input == 1) {
 		pix->colorspace = V4L2_COLORSPACE_SRGB;
 	} else {
-		sd_fmt.pad = s->pad_source;
-		sd_fmt.which = V4L2_SUBDEV_FORMAT_ACTIVE;
+		struct v4l2_subdev_format sd_fmt = {
+			.pad = s->pad_source,
+			.which = V4L2_SUBDEV_FORMAT_ACTIVE,
+		};
+
 		v4l2_subdev_call(s->sd, pad, get_fmt, NULL, &sd_fmt);
 		v4l2_fill_pix_format(pix, &sd_fmt.format);
 	}
···
 {
 	struct cobalt_stream *s = video_drvdata(file);
 	struct v4l2_pix_format *pix = &f->fmt.pix;
-	struct v4l2_subdev_format sd_fmt;
 
 	/* Check for min (QCIF) and max (Full HD) size */
 	if ((pix->width < 176) || (pix->height < 144)) {
···
 		pix->height = 1080;
 		pix->colorspace = V4L2_COLORSPACE_SRGB;
 	} else {
-		sd_fmt.pad = s->pad_source;
-		sd_fmt.which = V4L2_SUBDEV_FORMAT_ACTIVE;
+		struct v4l2_subdev_format sd_fmt = {
+			.pad = s->pad_source,
+			.which = V4L2_SUBDEV_FORMAT_ACTIVE,
+		};
+
 		v4l2_subdev_call(s->sd, pad, get_fmt, NULL, &sd_fmt);
 		v4l2_fill_pix_format(pix, &sd_fmt.format);
 	}

drivers/media/pci/intel/ipu3/ipu3-cio2-main.c

···
 		struct v4l2_subdev *sd =
 			media_entity_to_v4l2_subdev(pad->entity);
 
+		memset(fmt, 0, sizeof(*fmt));
 		fmt->which = V4L2_SUBDEV_FORMAT_ACTIVE;
 		fmt->pad = pad->index;
 		return v4l2_subdev_call(sd, pad, get_fmt, NULL, fmt);

drivers/media/platform/qcom/camss/camss-video.c

···
 static int video_get_subdev_format(struct camss_video *video,
 				   struct v4l2_format *format)
 {
-	struct v4l2_subdev_format fmt;
+	struct v4l2_subdev_format fmt = {
+		.which = V4L2_SUBDEV_FORMAT_ACTIVE,
+	};
 	struct v4l2_subdev *subdev;
 	u32 pad;
 	int ret;
···
 
 	memset(&fmt, 0, sizeof(fmt));
 	fmt.pad = pad;
-	fmt.which = V4L2_SUBDEV_FORMAT_ACTIVE;
 
 	ret = v4l2_subdev_call(subdev, pad, get_fmt, NULL, &fmt);
 	if (ret)

drivers/media/platform/renesas/vsp1/vsp1_video.c

···
 
 static int vsp1_video_verify_format(struct vsp1_video *video)
 {
-	struct v4l2_subdev_format fmt;
+	struct v4l2_subdev_format fmt = {
+		.which = V4L2_SUBDEV_FORMAT_ACTIVE,
+	};
 	struct v4l2_subdev *subdev;
 	int ret;
 
···
 	if (subdev == NULL)
 		return -EINVAL;
 
-	fmt.which = V4L2_SUBDEV_FORMAT_ACTIVE;
 	ret = v4l2_subdev_call(subdev, pad, get_fmt, NULL, &fmt);
 	if (ret < 0)
 		return ret == -ENOIOCTLCMD ? -EINVAL : ret;

drivers/media/platform/samsung/exynos4-is/fimc-capture.c

···
 				      struct v4l2_plane_pix_format *plane_fmt,
 				      unsigned int num_planes, bool try)
 {
-	struct v4l2_mbus_frame_desc fd;
+	struct v4l2_mbus_frame_desc fd = { };
 	int i, ret;
 	int pad;
 
···
  */
 static int fimc_pipeline_validate(struct fimc_dev *fimc)
 {
-	struct v4l2_subdev_format sink_fmt, src_fmt;
+	struct v4l2_subdev_format sink_fmt = {
+		.which = V4L2_SUBDEV_FORMAT_ACTIVE,
+	};
+	struct v4l2_subdev_format src_fmt = {
+		.which = V4L2_SUBDEV_FORMAT_ACTIVE,
+	};
 	struct fimc_vid_cap *vc = &fimc->vid_cap;
 	struct v4l2_subdev *sd = &vc->subdev;
 	struct fimc_pipeline *p = to_fimc_pipeline(vc->ve.pipe);
···
 			sink_fmt.format.code = ff->fmt ? ff->fmt->mbus_code : 0;
 		} else {
 			sink_fmt.pad = sink_pad->index;
-			sink_fmt.which = V4L2_SUBDEV_FORMAT_ACTIVE;
 			ret = v4l2_subdev_call(sd, pad, get_fmt, NULL, &sink_fmt);
 			if (ret < 0 && ret != -ENOIOCTLCMD)
 				return -EPIPE;
···
 		/* Retrieve format at the source pad */
 		sd = media_entity_to_v4l2_subdev(src_pad->entity);
 		src_fmt.pad = src_pad->index;
-		src_fmt.which = V4L2_SUBDEV_FORMAT_ACTIVE;
 		ret = v4l2_subdev_call(sd, pad, get_fmt, NULL, &src_fmt);
 		if (ret < 0 && ret != -ENOIOCTLCMD)
 			return -EPIPE;

drivers/media/platform/samsung/exynos4-is/fimc-isp-video.c

···
 static int isp_video_pipeline_validate(struct fimc_isp *isp)
 {
 	struct v4l2_subdev *sd = &isp->subdev;
-	struct v4l2_subdev_format sink_fmt, src_fmt;
 	struct media_pad *pad;
 	int ret;
 
 	while (1) {
+		struct v4l2_subdev_format sink_fmt = {
+			.which = V4L2_SUBDEV_FORMAT_ACTIVE,
+		};
+		struct v4l2_subdev_format src_fmt = {
+			.which = V4L2_SUBDEV_FORMAT_ACTIVE,
+		};
+
 		/* Retrieve format at the sink pad */
 		pad = &sd->entity.pads[0];
 		if (!(pad->flags & MEDIA_PAD_FL_SINK))
 			break;
 		sink_fmt.pad = pad->index;
-		sink_fmt.which = V4L2_SUBDEV_FORMAT_ACTIVE;
 		ret = v4l2_subdev_call(sd, pad, get_fmt, NULL, &sink_fmt);
 		if (ret < 0 && ret != -ENOIOCTLCMD)
 			return -EPIPE;
···
 
 		sd = media_entity_to_v4l2_subdev(pad->entity);
 		src_fmt.pad = pad->index;
-		src_fmt.which = V4L2_SUBDEV_FORMAT_ACTIVE;
 		ret = v4l2_subdev_call(sd, pad, get_fmt, NULL, &src_fmt);
 		if (ret < 0 && ret != -ENOIOCTLCMD)
 			return -EPIPE;

drivers/media/platform/samsung/exynos4-is/fimc-lite.c

···
 static int fimc_pipeline_validate(struct fimc_lite *fimc)
 {
 	struct v4l2_subdev *sd = &fimc->subdev;
-	struct v4l2_subdev_format sink_fmt, src_fmt;
+	struct v4l2_subdev_format sink_fmt = {
+		.which = V4L2_SUBDEV_FORMAT_ACTIVE,
+	};
+	struct v4l2_subdev_format src_fmt = {
+		.which = V4L2_SUBDEV_FORMAT_ACTIVE,
+	};
 	struct media_pad *pad;
 	int ret;
 
···
 			sink_fmt.format.code = fimc->inp_frame.fmt->mbus_code;
 		} else {
 			sink_fmt.pad = pad->index;
-			sink_fmt.which = V4L2_SUBDEV_FORMAT_ACTIVE;
 			ret = v4l2_subdev_call(sd, pad, get_fmt, NULL,
 					       &sink_fmt);
 			if (ret < 0 && ret != -ENOIOCTLCMD)
···
 
 		sd = media_entity_to_v4l2_subdev(pad->entity);
 		src_fmt.pad = pad->index;
-		src_fmt.which = V4L2_SUBDEV_FORMAT_ACTIVE;
 		ret = v4l2_subdev_call(sd, pad, get_fmt, NULL, &src_fmt);
 		if (ret < 0 && ret != -ENOIOCTLCMD)
 			return -EPIPE;

drivers/media/platform/samsung/s3c-camif/camif-capture.c

···
 /* Only check pixel formats at the sensor and the camif subdev pads */
 static int camif_pipeline_validate(struct camif_dev *camif)
 {
-	struct v4l2_subdev_format src_fmt;
+	struct v4l2_subdev_format src_fmt = {
+		.which = V4L2_SUBDEV_FORMAT_ACTIVE,
+	};
 	struct media_pad *pad;
 	int ret;
 
···
 		return -EPIPE;
 
 	src_fmt.pad = pad->index;
-	src_fmt.which = V4L2_SUBDEV_FORMAT_ACTIVE;
 	ret = v4l2_subdev_call(camif->sensor.sd, pad, get_fmt, NULL, &src_fmt);
 	if (ret < 0 && ret != -ENOIOCTLCMD)
 		return -EPIPE;

drivers/media/platform/samsung/s3c-camif/camif-core.c

···
 	struct s3c_camif_sensor_info *sensor = &camif->pdata.sensor;
 	struct v4l2_device *v4l2_dev = &camif->v4l2_dev;
 	struct i2c_adapter *adapter;
-	struct v4l2_subdev_format format;
+	struct v4l2_subdev_format format = {
+		.which = V4L2_SUBDEV_FORMAT_ACTIVE,
+	};
 	struct v4l2_subdev *sd;
 	int ret;
 
···
 
 	/* Get initial pixel format and set it at the camif sink pad */
 	format.pad = 0;
-	format.which = V4L2_SUBDEV_FORMAT_ACTIVE;
 	ret = v4l2_subdev_call(sd, pad, get_fmt, NULL, &format);
 
 	if (ret < 0)

drivers/media/platform/ti/am437x/am437x-vpfe.c

···
 			       struct v4l2_mbus_framefmt *fmt)
 {
 	struct v4l2_subdev *sd = vpfe->current_subdev->sd;
-	struct v4l2_subdev_format sd_fmt;
+	struct v4l2_subdev_format sd_fmt = {
+		.which = V4L2_SUBDEV_FORMAT_ACTIVE,
+		.pad = 0,
+	};
 	struct v4l2_mbus_framefmt *mbus_fmt = &sd_fmt.format;
 	int ret;
-
-	sd_fmt.which = V4L2_SUBDEV_FORMAT_ACTIVE;
-	sd_fmt.pad = 0;
 
 	ret = v4l2_subdev_call(sd, pad, get_fmt, NULL, &sd_fmt);
 	if (ret)
···
 			       struct v4l2_mbus_framefmt *fmt)
 {
 	struct v4l2_subdev *sd = vpfe->current_subdev->sd;
-	struct v4l2_subdev_format sd_fmt;
+	struct v4l2_subdev_format sd_fmt = {
+		.which = V4L2_SUBDEV_FORMAT_ACTIVE,
+		.pad = 0,
+	};
 	struct v4l2_mbus_framefmt *mbus_fmt = &sd_fmt.format;
 	int ret;
 
-	sd_fmt.which = V4L2_SUBDEV_FORMAT_ACTIVE;
-	sd_fmt.pad = 0;
 	*mbus_fmt = *fmt;
 
 	ret = v4l2_subdev_call(sd, pad, set_fmt, NULL, &sd_fmt);
···
 	struct vpfe_device *vpfe = video_drvdata(file);
 	struct v4l2_subdev *sd = vpfe->current_subdev->sd;
 	const struct vpfe_fmt *fmt;
-	struct v4l2_subdev_frame_size_enum fse;
+	struct v4l2_subdev_frame_size_enum fse = {
+		.which = V4L2_SUBDEV_FORMAT_ACTIVE,
+	};
 	int ret, found;
 
 	fmt = find_format_by_pix(vpfe, f->fmt.pix.pixelformat);
···
 	found = false;
 	fse.pad = 0;
 	fse.code = fmt->code;
-	fse.which = V4L2_SUBDEV_FORMAT_ACTIVE;
 	for (fse.index = 0; ; fse.index++) {
 		ret = v4l2_subdev_call(sd, pad, enum_frame_size,
 				       NULL, &fse);

drivers/media/platform/ti/cal/cal-video.c

···
 static int __subdev_get_format(struct cal_ctx *ctx,
 			       struct v4l2_mbus_framefmt *fmt)
 {
-	struct v4l2_subdev_format sd_fmt;
+	struct v4l2_subdev_format sd_fmt = {
+		.which = V4L2_SUBDEV_FORMAT_ACTIVE,
+		.pad = 0,
+	};
 	struct v4l2_mbus_framefmt *mbus_fmt = &sd_fmt.format;
 	int ret;
-
-	sd_fmt.which = V4L2_SUBDEV_FORMAT_ACTIVE;
-	sd_fmt.pad = 0;
 
 	ret = v4l2_subdev_call(ctx->phy->source, pad, get_fmt, NULL, &sd_fmt);
 	if (ret)
···
 static int __subdev_set_format(struct cal_ctx *ctx,
 			       struct v4l2_mbus_framefmt *fmt)
 {
-	struct v4l2_subdev_format sd_fmt;
+	struct v4l2_subdev_format sd_fmt = {
+		.which = V4L2_SUBDEV_FORMAT_ACTIVE,
+		.pad = 0,
+	};
 	struct v4l2_mbus_framefmt *mbus_fmt = &sd_fmt.format;
 	int ret;
 
-	sd_fmt.which = V4L2_SUBDEV_FORMAT_ACTIVE;
-	sd_fmt.pad = 0;
 	*mbus_fmt = *fmt;
 
 	ret = v4l2_subdev_call(ctx->phy->source, pad, set_fmt, NULL, &sd_fmt);
···
 {
 	struct cal_ctx *ctx = video_drvdata(file);
 	const struct cal_format_info *fmtinfo;
-	struct v4l2_subdev_frame_size_enum fse;
+	struct v4l2_subdev_frame_size_enum fse = {
+		.which = V4L2_SUBDEV_FORMAT_ACTIVE,
+	};
 	int found;
 
 	fmtinfo = find_format_by_pix(ctx, f->fmt.pix.pixelformat);
···
 	found = false;
 	fse.pad = 0;
 	fse.code = fmtinfo->code;
-	fse.which = V4L2_SUBDEV_FORMAT_ACTIVE;
 	for (fse.index = 0; ; fse.index++) {
 		int ret;
 
···
 {
 	struct cal_ctx *ctx = video_drvdata(file);
 	const struct cal_format_info *fmtinfo;
-	struct v4l2_subdev_frame_size_enum fse;
+	struct v4l2_subdev_frame_size_enum fse = {
+		.index = fsize->index,
+		.pad = 0,
+		.which = V4L2_SUBDEV_FORMAT_ACTIVE,
+	};
 	int ret;
 
 	/* check for valid format */
···
 		return -EINVAL;
 	}
 
-	fse.index = fsize->index;
-	fse.pad = 0;
 	fse.code = fmtinfo->code;
-	fse.which = V4L2_SUBDEV_FORMAT_ACTIVE;
 
 	ret = v4l2_subdev_call(ctx->phy->source, pad, enum_frame_size, NULL,
 			       &fse);

drivers/media/platform/ti/omap3isp/ispccdc.c

···
 	struct v4l2_mbus_framefmt *format;
 	const struct v4l2_rect *crop;
 	const struct isp_format_info *fmt_info;
-	struct v4l2_subdev_format fmt_src;
+	struct v4l2_subdev_format fmt_src = {
+		.which = V4L2_SUBDEV_FORMAT_ACTIVE,
+	};
 	unsigned int depth_out;
 	unsigned int depth_in = 0;
 	struct media_pad *pad;
···
 	 * input format is a non-BT.656 YUV variant.
 	 */
 	fmt_src.pad = pad->index;
-	fmt_src.which = V4L2_SUBDEV_FORMAT_ACTIVE;
 	if (!v4l2_subdev_call(sensor, pad, get_fmt, NULL, &fmt_src)) {
 		fmt_info = omap3isp_video_format_info(fmt_src.format.code);
 		depth_in = fmt_info->width;

drivers/media/platform/ti/omap3isp/ispvideo.c

···
 static int
 __isp_video_get_format(struct isp_video *video, struct v4l2_format *format)
 {
-	struct v4l2_subdev_format fmt;
+	struct v4l2_subdev_format fmt = {
+		.which = V4L2_SUBDEV_FORMAT_ACTIVE,
+	};
 	struct v4l2_subdev *subdev;
 	u32 pad;
 	int ret;
···
 		return -EINVAL;
 
 	fmt.pad = pad;
-	fmt.which = V4L2_SUBDEV_FORMAT_ACTIVE;
 
 	mutex_lock(&video->mutex);
 	ret = v4l2_subdev_call(subdev, pad, get_fmt, NULL, &fmt);
···
 isp_video_try_format(struct file *file, void *fh, struct v4l2_format *format)
 {
 	struct isp_video *video = video_drvdata(file);
-	struct v4l2_subdev_format fmt;
+	struct v4l2_subdev_format fmt = {
+		.which = V4L2_SUBDEV_FORMAT_ACTIVE,
+	};
 	struct v4l2_subdev *subdev;
 	u32 pad;
 	int ret;
···
 	isp_video_pix_to_mbus(&format->fmt.pix, &fmt.format);
 
 	fmt.pad = pad;
-	fmt.which = V4L2_SUBDEV_FORMAT_ACTIVE;
 	ret = v4l2_subdev_call(subdev, pad, get_fmt, NULL, &fmt);
 	if (ret)
 		return ret == -ENOIOCTLCMD ? -ENOTTY : ret;
···
 isp_video_get_selection(struct file *file, void *fh, struct v4l2_selection *sel)
 {
 	struct isp_video *video = video_drvdata(file);
-	struct v4l2_subdev_format format;
+	struct v4l2_subdev_format format = {
+		.which = V4L2_SUBDEV_FORMAT_ACTIVE,
+	};
 	struct v4l2_subdev *subdev;
 	struct v4l2_subdev_selection sdsel = {
 		.which = V4L2_SUBDEV_FORMAT_ACTIVE,
···
 		return ret;
 
 	format.pad = pad;
-	format.which = V4L2_SUBDEV_FORMAT_ACTIVE;
 	ret = v4l2_subdev_call(subdev, pad, get_fmt, NULL, &format);
 	if (ret < 0)
 		return ret == -ENOIOCTLCMD ? -ENOTTY : ret;
···
 	struct media_pad *source_pad;
 	struct media_entity *source = NULL;
 	struct media_entity *sink;
-	struct v4l2_subdev_format fmt;
+	struct v4l2_subdev_format fmt = {
+		.which = V4L2_SUBDEV_FORMAT_ACTIVE,
+	};
 	struct v4l2_ext_controls ctrls;
 	struct v4l2_ext_control ctrl;
 	unsigned int i;
···
 	pipe->external = media_entity_to_v4l2_subdev(source);
 
 	fmt.pad = source_pad->index;
-	fmt.which = V4L2_SUBDEV_FORMAT_ACTIVE;
 	ret = v4l2_subdev_call(media_entity_to_v4l2_subdev(sink),
 			       pad, get_fmt, NULL, &fmt);
 	if (unlikely(ret < 0)) {

drivers/media/platform/xilinx/xilinx-dma.c

···
 
 static int xvip_dma_verify_format(struct xvip_dma *dma)
 {
-	struct v4l2_subdev_format fmt;
+	struct v4l2_subdev_format fmt = {
+		.which = V4L2_SUBDEV_FORMAT_ACTIVE,
+	};
 	struct v4l2_subdev *subdev;
 	int ret;
 
···
 	if (subdev == NULL)
 		return -EPIPE;
 
-	fmt.which = V4L2_SUBDEV_FORMAT_ACTIVE;
 	ret = v4l2_subdev_call(subdev, pad, get_fmt, NULL, &fmt);
 	if (ret < 0)
 		return ret == -ENOIOCTLCMD ? -EINVAL : ret;

drivers/media/test-drivers/vimc/vimc-common.c

···
 	if (is_media_entity_v4l2_subdev(pad->entity)) {
 		struct v4l2_subdev *sd =
 			media_entity_to_v4l2_subdev(pad->entity);
-		struct v4l2_subdev_format sd_fmt;
+		struct v4l2_subdev_format sd_fmt = {
+			.which = V4L2_SUBDEV_FORMAT_ACTIVE,
+			.pad = pad->index,
+		};
 		const struct vimc_pix_map *pix_map;
 		int ret;
-
-		sd_fmt.which = V4L2_SUBDEV_FORMAT_ACTIVE;
-		sd_fmt.pad = pad->index;
 
 		ret = v4l2_subdev_call(sd, pad, get_fmt, NULL, &sd_fmt);
 		if (ret)

drivers/staging/media/imx/imx-media-capture.c

···
 {
 	struct capture_priv *priv = video_drvdata(file);
 	const struct imx_media_pixfmt *cc_src;
-	struct v4l2_subdev_format fmt_src;
+	struct v4l2_subdev_format fmt_src = {
+		.pad = priv->src_sd_pad,
+		.which = V4L2_SUBDEV_FORMAT_ACTIVE,
+	};
 	u32 fourcc;
 	int ret;
 
-	fmt_src.pad = priv->src_sd_pad;
-	fmt_src.which = V4L2_SUBDEV_FORMAT_ACTIVE;
 	ret = v4l2_subdev_call(priv->src_sd, pad, get_fmt, NULL, &fmt_src);
 	if (ret) {
 		dev_err(priv->dev, "failed to get src_sd format\n");
···
 					  struct v4l2_format *f)
 {
 	struct capture_priv *priv = video_drvdata(file);
-	struct v4l2_subdev_format fmt_src;
+	struct v4l2_subdev_format fmt_src = {
+		.pad = priv->src_sd_pad,
+		.which = V4L2_SUBDEV_FORMAT_ACTIVE,
+	};
 	int ret;
 
-	fmt_src.pad = priv->src_sd_pad;
-	fmt_src.which = V4L2_SUBDEV_FORMAT_ACTIVE;
 	ret = v4l2_subdev_call(priv->src_sd, pad, get_fmt, NULL, &fmt_src);
 	if (ret)
 		return ret;
···
 					struct v4l2_format *f)
 {
 	struct capture_priv *priv = video_drvdata(file);
-	struct v4l2_subdev_format fmt_src;
+	struct v4l2_subdev_format fmt_src = {
+		.pad = priv->src_sd_pad,
+		.which = V4L2_SUBDEV_FORMAT_ACTIVE,
+	};
 	const struct imx_media_pixfmt *cc;
 	int ret;
 
···
 		return -EBUSY;
 	}
 
-	fmt_src.pad = priv->src_sd_pad;
-	fmt_src.which = V4L2_SUBDEV_FORMAT_ACTIVE;
 	ret = v4l2_subdev_call(priv->src_sd, pad, get_fmt, NULL, &fmt_src);
 	if (ret)
 		return ret;
···
 
 static int capture_validate_fmt(struct capture_priv *priv)
 {
-	struct v4l2_subdev_format fmt_src;
+	struct v4l2_subdev_format fmt_src = {
+		.pad = priv->src_sd_pad,
+		.which = V4L2_SUBDEV_FORMAT_ACTIVE,
+	};
 	const struct imx_media_pixfmt *cc;
 	int ret;
 
 	/* Retrieve the media bus format on the source subdev. */
-	fmt_src.pad = priv->src_sd_pad;
-	fmt_src.which = V4L2_SUBDEV_FORMAT_ACTIVE;
 	ret = v4l2_subdev_call(priv->src_sd, pad, get_fmt, NULL, &fmt_src);
 	if (ret)
 		return ret;

drivers/staging/media/omap4iss/iss_video.c

···
 iss_video_try_format(struct file *file, void *fh, struct v4l2_format *format)
 {
 	struct iss_video *video = video_drvdata(file);
-	struct v4l2_subdev_format fmt;
+	struct v4l2_subdev_format fmt = {
+		.which = V4L2_SUBDEV_FORMAT_ACTIVE,
+	};
 	struct v4l2_subdev *subdev;
 	u32 pad;
 	int ret;
···
 	iss_video_pix_to_mbus(&format->fmt.pix, &fmt.format);
 
 	fmt.pad = pad;
-	fmt.which = V4L2_SUBDEV_FORMAT_ACTIVE;
 	ret = v4l2_subdev_call(subdev, pad, get_fmt, NULL, &fmt);
 	if (ret)
 		return ret;
···
 iss_video_get_selection(struct file *file, void *fh, struct v4l2_selection *sel)
 {
 	struct iss_video *video = video_drvdata(file);
-	struct v4l2_subdev_format format;
+	struct v4l2_subdev_format format = {
+		.which = V4L2_SUBDEV_FORMAT_ACTIVE,
+	};
 	struct v4l2_subdev *subdev;
 	struct v4l2_subdev_selection sdsel = {
 		.which = V4L2_SUBDEV_FORMAT_ACTIVE,
···
 		return ret;
 
 	format.pad = pad;
-	format.which = V4L2_SUBDEV_FORMAT_ACTIVE;
 	ret = v4l2_subdev_call(subdev, pad, get_fmt, NULL, &format);
 	if (ret < 0)
 		return ret == -ENOIOCTLCMD ? -ENOTTY : ret;

drivers/staging/media/tegra-video/vi.c

···
 	const struct tegra_video_format *fmtinfo;
 	static struct lock_class_key key;
 	struct v4l2_subdev *subdev;
-	struct v4l2_subdev_format fmt;
+	struct v4l2_subdev_format fmt = {
+		.which = V4L2_SUBDEV_FORMAT_TRY,
+	};
 	struct v4l2_subdev_state *sd_state;
 	struct v4l2_subdev_frame_size_enum fse = {
 		.which = V4L2_SUBDEV_FORMAT_TRY,
···
 	}
 
 	pix->field = V4L2_FIELD_NONE;
-	fmt.which = V4L2_SUBDEV_FORMAT_TRY;
 	fmt.pad = 0;
 	v4l2_fill_mbus_format(&fmt.format, pix, fmtinfo->code);
 
···
 {
 	struct tegra_vi_channel *chan = video_drvdata(file);
 	const struct tegra_video_format *fmtinfo;
-	struct v4l2_subdev_format fmt;
+	struct v4l2_subdev_format fmt = {
+		.which = V4L2_SUBDEV_FORMAT_ACTIVE,
+	};
 	struct v4l2_subdev *subdev;
 	struct v4l2_pix_format *pix = &format->fmt.pix;
 	int ret;
···
 
 	fmtinfo = tegra_get_format_by_fourcc(chan->vi, pix->pixelformat);
 
-	fmt.which = V4L2_SUBDEV_FORMAT_ACTIVE;
 	fmt.pad = 0;
 	v4l2_fill_mbus_format(&fmt.format, pix, fmtinfo->code);
 	subdev = tegra_channel_get_remote_source_subdev(chan);