V4L/DVB (12075): gspca_ov519: check ov518 packet numbers

Check ov518 packet numbers to detect dropped packets.

Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>

1 files changed, 23 insertions, 6 deletions

diff --git a/drivers/media/video/gspca/ov519.c b/drivers/media/video/gspca/ov519.c
index 55db32c95bea..c2982137dc21 100644
--- a/drivers/media/video/gspca/ov519.c
+++ b/drivers/media/video/gspca/ov519.c
@@ -50,6 +50,8 @@ static int i2c_detect_tries = 10;
 struct sd {
         struct gspca_dev gspca_dev;             /* !! must be the first item */
 
+        __u8 packet_nr;
+
         char bridge;
 #define BRIDGE_OV511            0
 #define BRIDGE_OV511PLUS        1
@@ -2391,18 +2393,33 @@ static void ov518_pkt_scan(struct gspca_dev *gspca_dev,
                         __u8 *data,                     /* isoc packet */
                         int len)                        /* iso packet length */
 {
-        PDEBUG(D_STREAM, "ov518_pkt_scan: %d bytes", len);
-
-        if (len & 7) {
-                len--;
-                PDEBUG(D_STREAM, "packet number: %d\n", (int)data[len]);
-        }
+        struct sd *sd = (struct sd *) gspca_dev;
 
         /* A false positive here is likely, until OVT gives me
          * the definitive SOF/EOF format */
         if ((!(data[0] | data[1] | data[2] | data[3] | data[5])) && data[6]) {
                 gspca_frame_add(gspca_dev, LAST_PACKET, frame, data, 0);
                 gspca_frame_add(gspca_dev, FIRST_PACKET, frame, data, 0);
+                sd->packet_nr = 0;
+        }
+
+        if (gspca_dev->last_packet_type == DISCARD_PACKET)
+                return;
+
+        /* Does this device use packet numbers ? */
+        if (len & 7) {
+                len--;
+                if (sd->packet_nr == data[len])
+                        sd->packet_nr++;
+                /* The last few packets of the frame (which are all 0's
+                   except that they may contain part of the footer), are
+                   numbered 0 */
+                else if (sd->packet_nr == 0 || data[len]) {
+                        PDEBUG(D_ERR, "Invalid packet nr: %d (expect: %d)",
+                                (int)data[len], (int)sd->packet_nr);
+                        gspca_dev->last_packet_type = DISCARD_PACKET;
+                        return;
+                }
         }
 
         /* intermediate packet */