V4L/DVB (7548): Various fixes for the em28xx videobuf code

- Aborting buffer_filled if no-one's waiting on the waitqueue probably isn't
  what we want, since just because no-one's waiting for it now doesn't mean they
  wouldn't dequeue it in time. (vivi gets away with this, possibly because it
  can fill each buffer much faster.)

- The first BUG_ON(lencopy <= 0); really isn't worth causing a kernel panic
  over, especially since there are some reasons why it could trigger in normal use.

- The top and botom frames are actually the wrong way around.

Signed-off-by: Aidan Thornton <makosoft@googlemail.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@infradead.org>

1 files changed, 7 insertions, 13 deletions

diff --git a/drivers/media/video/em28xx/em28xx-video.c b/drivers/media/video/em28xx/em28xx-video.c
index 033ecb45256b..e2d04cf4ba9d 100644
--- a/drivers/media/video/em28xx/em28xx-video.c
+++ b/drivers/media/video/em28xx/em28xx-video.c
@@ -135,14 +135,6 @@ static inline void buffer_filled(struct em28xx *dev,
 {
         mod_timer(&dma_q->timeout, jiffies+BUFFER_TIMEOUT);
 
-        /* Nobody is waiting something to be done, just return */
-        if (!waitqueue_active(&buf->vb.done)) {
-                printk(KERN_ERR "em28xx: buffer underrun at %ld\n",
-                                jiffies);
-
-                return;
-        }
-
         /* Advice that buffer was filled */
         em28xx_isocdbg("[%p/%d] wakeup\n", buf, buf->vb.i);
         buf->vb.state = VIDEOBUF_DONE;
@@ -202,7 +194,8 @@ static void em28xx_copy_video(struct em28xx *dev,
                                ((char *)outp + buf->vb.size));
                 lencopy = remain = (char *)outp + buf->vb.size - (char *)startwrite;
         }
-        BUG_ON(lencopy <= 0);
+        if (lencopy <= 0)
+                return;
         memcpy(startwrite, startread, lencopy);
 
         remain -= lencopy;
@@ -356,11 +349,13 @@ static inline int em28xx_isoc_copy(struct urb *urb)
                 if (p[0] == 0x22 && p[1] == 0x5a) {
                         /* FIXME - are the fields the right way around? */
                         em28xx_isocdbg("Video frame, length=%i, %s\n", len,
-                                        (p[2] & 1)? "top" : "bottom");
+                                        (p[2] & 1)? "odd" : "even");
                         em28xx_isocdbg("Current buffer is: outp = 0x%p,"
                                        " len = %i\n", outp, (int)buf->vb.size);
 
-                        if (p[2] & 1) {
+                        if (p[2] & 1)
+                                buf->top_field = 0;
+                        else {
                                 if (buf->receiving) {
                                         buffer_filled(dev, dma_q, buf);
                                         rc = get_next_buf(dma_q, &buf);
@@ -371,8 +366,7 @@ static inline int em28xx_isoc_copy(struct urb *urb)
                                 }
 
                                 buf->top_field = 1;
-                        } else
-                                buf->top_field = 0;
+                        }
                         buf->receiving = 1;
                         dma_q->pos = 0;
                 } else if (p[0] == 0x33 && p[1] == 0x95 && p[2] == 0x00) {