[media] em28xx: fix capture type setting in em28xx_urb_data_copy_vbi()

Set capture type to 1 (video start) when the video frame start header is
detected. This bug didn't cause any trouble, because this type of header is
never received in vbi mode.
Fix it, because we want to use this function with disabled vbi in the future.
Also start with capture type -1 to avoid processing of corrupted/incomplete
frame data which is usually received at streaming start (especially when
USB bulk transfers are used).
Signed-off-by: Frank Schäfer <fschaefer.oss@googlemail.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>

drivers/media/usb/em28xx/em28xx-video.c

@@ -593,7 +593,7 @@ static inline int em28xx_urb_data_copy_vbi(struct em28xx *dev, struct urb *urb)
 				dev->capture_type = 0;
 				dev->vbi_read = 0;
 				em28xx_isocdbg("VBI START HEADER!!!\n");
-				dev->cur_field = p[2];
+				dev->top_field = !(p[2] & 1);
 				p += 4;
 				len -= 4;
 			} else if (p[0] == 0x88 && p[1] == 0x88 &&
@@ -603,6 +603,8 @@ static inline int em28xx_urb_data_copy_vbi(struct em28xx *dev, struct urb *urb)
 				len -= 4;
 			} else if (p[0] == 0x22 && p[1] == 0x5a) {
 				/* start video */
+				dev->capture_type = 1;
+				dev->top_field = !(p[2] & 1);
 				p += 4;
 				len -= 4;
 			}
@@ -619,8 +621,7 @@ static inline int em28xx_urb_data_copy_vbi(struct em28xx *dev, struct urb *urb)
 				em28xx_isocdbg("dev->vbi_read > vbi_size\n");
 			} else if ((dev->vbi_read + len) < vbi_size) {
 				/* This entire frame is VBI data */
-				if (dev->vbi_read == 0 &&
-				    (!(dev->cur_field & 1))) {
+				if (dev->vbi_read == 0 && dev->top_field) {
 					/* Brand new frame */
 					if (vbi_buf != NULL)
 						vbi_buffer_filled(dev,
@@ -636,12 +637,8 @@ static inline int em28xx_urb_data_copy_vbi(struct em28xx *dev, struct urb *urb)
 
 				if (dev->vbi_read == 0) {
 					vbi_dma_q->pos = 0;
-					if (vbi_buf != NULL) {
-						if (dev->cur_field & 1)
-							vbi_buf->top_field = 0;
-						else
-							vbi_buf->top_field = 1;
-					}
+					if (vbi_buf != NULL)
+						vbi_buf->top_field = dev->top_field;
 				}
 
 				dev->vbi_read += len;
@@ -662,7 +659,7 @@ static inline int em28xx_urb_data_copy_vbi(struct em28xx *dev, struct urb *urb)
 
 		if (dev->capture_type == 1) {
 			dev->capture_type = 2;
-			if (dev->progressive || !(dev->cur_field & 1)) {
+			if (dev->progressive || dev->top_field) {
 				if (buf != NULL)
 					buffer_filled(dev, dma_q, buf);
 				get_next_buf(dma_q, &buf);
@@ -671,12 +668,8 @@ static inline int em28xx_urb_data_copy_vbi(struct em28xx *dev, struct urb *urb)
 				else
 					outp = videobuf_to_vmalloc(&buf->vb);
 			}
-			if (buf != NULL) {
-				if (dev->cur_field & 1)
-					buf->top_field = 0;
-				else
-					buf->top_field = 1;
-			}
+			if (buf != NULL)
+				buf->top_field = dev->top_field;
 
 			dma_q->pos = 0;
 		}
@@ -774,6 +767,7 @@ buffer_prepare(struct videobuf_queue *vq, struct videobuf_buffer *vb,
 		urb_init = 1;
 
 	if (urb_init) {
+		dev->capture_type = -1;
 		if (em28xx_vbi_supported(dev) == 1)
 			rc = em28xx_init_usb_xfer(dev, EM28XX_ANALOG_MODE,
 						  dev->analog_xfer_bulk,

drivers/media/usb/em28xx/em28xx.h

@@ -563,7 +563,7 @@ struct em28xx {
 	/* vbi related state tracking */
 	int capture_type;
 	int vbi_read;
-	unsigned char cur_field;
+	unsigned char top_field:1;
 	unsigned int vbi_width;
 	unsigned int vbi_height; /* lines per field */