media: uvcvideo: Constify formats, frames and intervals

The formats, frames and intervals stored in the uvc_streaming structure
are not meant to change after being parsed at probe time. Make them
const to prevent unintended modifications, and adapt the probe code
accordingly to use non-const pointers during parsing.
Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Reviewed-by: Ricardo Ribalda <ribalda@chromium.org>
Signed-off-by: Mauro Carvalho Chehab <mchehab@kernel.org>

drivers/media/usb/uvc/uvc_driver.c

@@ -221,7 +221,8 @@ static struct uvc_streaming *uvc_stream_new(struct uvc_device *dev,
 
 static int uvc_parse_format(struct uvc_device *dev,
 	struct uvc_streaming *streaming, struct uvc_format *format,
-	u32 **intervals, unsigned char *buffer, int buflen)
+	struct uvc_frame *frames, u32 **intervals, unsigned char *buffer,
+	int buflen)
 {
 	struct usb_interface *intf = streaming->intf;
 	struct usb_host_interface *alts = intf->cur_altsetting;
@@ -235,6 +236,7 @@ static int uvc_parse_format(struct uvc_device *dev,
 
 	format->type = buffer[2];
 	format->index = buffer[3];
+	format->frames = frames;
 
 	switch (buffer[2]) {
 	case UVC_VS_FORMAT_UNCOMPRESSED:
@@ -339,8 +341,8 @@ static int uvc_parse_format(struct uvc_device *dev,
 		ftype = 0;
 
 		/* Create a dummy frame descriptor. */
-		frame = &format->frames[0];
-		memset(&format->frames[0], 0, sizeof(format->frames[0]));
+		frame = &frames[0];
+		memset(frame, 0, sizeof(*frame));
 		frame->bFrameIntervalType = 1;
 		frame->dwDefaultFrameInterval = 1;
 		frame->dwFrameInterval = *intervals;
@@ -372,7 +374,7 @@ static int uvc_parse_format(struct uvc_device *dev,
 	       buffer[2] == ftype) {
 		unsigned int maxIntervalIndex;
 
-		frame = &format->frames[format->nframes];
+		frame = &frames[format->nframes];
 		if (ftype != UVC_VS_FRAME_FRAME_BASED)
 			n = buflen > 25 ? buffer[25] : 0;
 		else
@@ -460,8 +462,7 @@ static int uvc_parse_format(struct uvc_device *dev,
 		 */
 		if (dev->quirks & UVC_QUIRK_RESTRICT_FRAME_RATE) {
 			frame->bFrameIntervalType = 1;
-			frame->dwFrameInterval[0] =
-				frame->dwDefaultFrameInterval;
+			(*intervals)[0] = frame->dwDefaultFrameInterval;
 		}
 
 		uvc_dbg(dev, DESCR, "- %ux%u (%u.%u fps)\n",
@@ -706,8 +707,7 @@ static int uvc_parse_streaming(struct uvc_device *dev,
 		case UVC_VS_FORMAT_MJPEG:
 		case UVC_VS_FORMAT_DV:
 		case UVC_VS_FORMAT_FRAME_BASED:
-			format->frames = frame;
-			ret = uvc_parse_format(dev, streaming, format,
+			ret = uvc_parse_format(dev, streaming, format, frame,
 				&interval, buffer, buflen);
 			if (ret < 0)
 				goto error;

drivers/media/usb/uvc/uvc_v4l2.c

@@ -161,7 +161,7 @@ static int uvc_ioctl_xu_ctrl_map(struct uvc_video_chain *chain,
  * the Video Probe and Commit negotiation, but some hardware don't implement
  * that feature.
  */
-static u32 uvc_try_frame_interval(struct uvc_frame *frame, u32 interval)
+static u32 uvc_try_frame_interval(const struct uvc_frame *frame, u32 interval)
 {
 	unsigned int i;
 
@@ -210,10 +210,11 @@ static u32 uvc_v4l2_get_bytesperline(const struct uvc_format *format,
 
 static int uvc_v4l2_try_format(struct uvc_streaming *stream,
 	struct v4l2_format *fmt, struct uvc_streaming_control *probe,
-	struct uvc_format **uvc_format, struct uvc_frame **uvc_frame)
+	const struct uvc_format **uvc_format,
+	const struct uvc_frame **uvc_frame)
 {
-	struct uvc_format *format = NULL;
-	struct uvc_frame *frame = NULL;
+	const struct uvc_format *format = NULL;
+	const struct uvc_frame *frame = NULL;
 	u16 rw, rh;
 	unsigned int d, maxd;
 	unsigned int i;
@@ -363,8 +364,8 @@ static int uvc_v4l2_try_format(struct uvc_streaming *stream,
 static int uvc_v4l2_get_format(struct uvc_streaming *stream,
 	struct v4l2_format *fmt)
 {
-	struct uvc_format *format;
-	struct uvc_frame *frame;
+	const struct uvc_format *format;
+	const struct uvc_frame *frame;
 	int ret = 0;
 
 	if (fmt->type != stream->type)
@@ -398,8 +399,8 @@ static int uvc_v4l2_set_format(struct uvc_streaming *stream,
 	struct v4l2_format *fmt)
 {
 	struct uvc_streaming_control probe;
-	struct uvc_format *format;
-	struct uvc_frame *frame;
+	const struct uvc_format *format;
+	const struct uvc_frame *frame;
 	int ret;
 
 	if (fmt->type != stream->type)
@@ -465,8 +466,8 @@ static int uvc_v4l2_set_streamparm(struct uvc_streaming *stream,
 {
 	struct uvc_streaming_control probe;
 	struct v4l2_fract timeperframe;
-	struct uvc_format *format;
-	struct uvc_frame *frame;
+	const struct uvc_format *format;
+	const struct uvc_frame *frame;
 	u32 interval, maxd;
 	unsigned int i;
 	int ret;
@@ -697,7 +698,7 @@ static int uvc_ioctl_querycap(struct file *file, void *fh,
 static int uvc_ioctl_enum_fmt(struct uvc_streaming *stream,
 			      struct v4l2_fmtdesc *fmt)
 {
-	struct uvc_format *format;
+	const struct uvc_format *format;
 	enum v4l2_buf_type type = fmt->type;
 	u32 index = fmt->index;
 
@@ -1249,8 +1250,8 @@ static int uvc_ioctl_enum_framesizes(struct file *file, void *fh,
 {
 	struct uvc_fh *handle = fh;
 	struct uvc_streaming *stream = handle->stream;
-	struct uvc_format *format = NULL;
-	struct uvc_frame *frame = NULL;
+	const struct uvc_format *format = NULL;
+	const struct uvc_frame *frame = NULL;
 	unsigned int index;
 	unsigned int i;
 
@@ -1289,8 +1290,8 @@ static int uvc_ioctl_enum_frameintervals(struct file *file, void *fh,
 {
 	struct uvc_fh *handle = fh;
 	struct uvc_streaming *stream = handle->stream;
-	struct uvc_format *format = NULL;
-	struct uvc_frame *frame = NULL;
+	const struct uvc_format *format = NULL;
+	const struct uvc_frame *frame = NULL;
 	unsigned int nintervals;
 	unsigned int index;
 	unsigned int i;

drivers/media/usb/uvc/uvc_video.c

@@ -137,8 +137,8 @@ static const struct usb_device_id elgato_cam_link_4k = {
 static void uvc_fixup_video_ctrl(struct uvc_streaming *stream,
 	struct uvc_streaming_control *ctrl)
 {
-	struct uvc_format *format = NULL;
-	struct uvc_frame *frame = NULL;
+	const struct uvc_format *format = NULL;
+	const struct uvc_frame *frame = NULL;
 	unsigned int i;
 
 	/*
@@ -2100,8 +2100,8 @@ int uvc_video_resume(struct uvc_streaming *stream, int reset)
 int uvc_video_init(struct uvc_streaming *stream)
 {
 	struct uvc_streaming_control *probe = &stream->ctrl;
-	struct uvc_format *format = NULL;
-	struct uvc_frame *frame = NULL;
+	const struct uvc_format *format = NULL;
+	const struct uvc_frame *frame = NULL;
 	struct uvc_urb *uvc_urb;
 	unsigned int i;
 	int ret;

drivers/media/usb/uvc/uvcvideo.h

@@ -251,7 +251,7 @@ struct uvc_frame {
 	u32 dwMaxVideoFrameBufferSize;
 	u8  bFrameIntervalType;
 	u32 dwDefaultFrameInterval;
-	u32 *dwFrameInterval;
+	const u32 *dwFrameInterval;
 };
 
 struct uvc_format {
@@ -265,7 +265,7 @@ struct uvc_format {
 	u32 flags;
 
 	unsigned int nframes;
-	struct uvc_frame *frames;
+	const struct uvc_frame *frames;
 };
 
 struct uvc_streaming_header {
@@ -438,12 +438,12 @@ struct uvc_streaming {
 	enum v4l2_buf_type type;
 
 	unsigned int nformats;
-	struct uvc_format *formats;
+	const struct uvc_format *formats;
 
 	struct uvc_streaming_control ctrl;
-	struct uvc_format *def_format;
-	struct uvc_format *cur_format;
-	struct uvc_frame *cur_frame;
+	const struct uvc_format *def_format;
+	const struct uvc_format *cur_format;
+	const struct uvc_frame *cur_frame;
 
 	/*
 	 * Protect access to ctrl, cur_format, cur_frame and hardware video