V4L/DVB: gspca_ovfx2: drop first frames in stream if not synced

With the ovfx2 bridge sometimes the first few frames in a stream
would be no good, as the bridge and sensor are not in complete hsync /
vsync yet. This can easily be detected by checking the framesize. So if the
framesize is short and it is one of the 1ste 3 frames after an sd_start,
drop it.

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

1 files changed, 18 insertions, 3 deletions

diff --git a/drivers/media/video/gspca/ov519.c b/drivers/media/video/gspca/ov519.c
index f36e11a0458d..aa3de2f5a272 100644
--- a/drivers/media/video/gspca/ov519.c
+++ b/drivers/media/video/gspca/ov519.c
@@ -90,6 +90,7 @@ struct sd {
 #define QUALITY_DEF 50
 
         __u8 stopped;           /* Streaming is temporarily paused */
+        __u8 first_frame;
 
         __u8 frame_rate;        /* current Framerate */
         __u8 clockdiv;          /* clockdiv override */
@@ -3961,6 +3962,8 @@ static int sd_start(struct gspca_dev *gspca_dev)
         sd_reset_snapshot(gspca_dev);
         sd->snapshot_pressed = 0;
 
+        sd->first_frame = 3;
+
         ret = ov51x_restart(sd);
         if (ret < 0)
                 goto out;
@@ -4153,13 +4156,25 @@ static void ovfx2_pkt_scan(struct gspca_dev *gspca_dev,
                         u8 *data,                       /* isoc packet */
                         int len)                        /* iso packet length */
 {
+        struct sd *sd = (struct sd *) gspca_dev;
+        struct gspca_frame *frame;
+
+        gspca_frame_add(gspca_dev, INTER_PACKET, data, len);
+
         /* A short read signals EOF */
         if (len < OVFX2_BULK_SIZE) {
-                gspca_frame_add(gspca_dev, LAST_PACKET, data, len);
+                /* If the frame is short, and it is one of the first ones
+                   the sensor and bridge are still syncing, so drop it. */
+                if (sd->first_frame) {
+                        sd->first_frame--;
+                        frame = gspca_get_i_frame(gspca_dev);
+                        if (!frame || (frame->data_end - frame->data) <
+                                  (sd->gspca_dev.width * sd->gspca_dev.height))
+                                gspca_dev->last_packet_type = DISCARD_PACKET;
+                }
+                gspca_frame_add(gspca_dev, LAST_PACKET, NULL, 0);
                 gspca_frame_add(gspca_dev, FIRST_PACKET, NULL, 0);
-                return;
         }
-        gspca_frame_add(gspca_dev, INTER_PACKET, data, len);
 }
 
 static void sd_pkt_scan(struct gspca_dev *gspca_dev,