V4L/DVB (7565): em28xx: fix buffer underrun handling

This patch fixes three related issues and a fourth trivial one:

- Use buffers even if no-one's currently waiting for them (fixes
  underrun issues);

- Don't return incomplete/mangled frames at the start of streaming and
  in the case of buffer underruns;

- Fix an issue which could cause the driver to write to a buffer that's
  been freed after videobuf_queue_cancel is called (exposed by the
  previous two fixes - for some reason, ignoring buffers that weren't
  being waited on worked around the issue);

- Fix a bug which could cause only one field to be filled in the first
  buffer (or first few buffers) after streaming is started.

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

1 files changed, 0 insertions, 3 deletions

diff --git a/drivers/media/video/em28xx/em28xx.h b/drivers/media/video/em28xx/em28xx.h
index 993c1ed05cc3..6d62357a038f 100644
--- a/drivers/media/video/em28xx/em28xx.h
+++ b/drivers/media/video/em28xx/em28xx.h
@@ -114,9 +114,6 @@ struct em28xx_usb_isoc_ctl {
                 /* Stores already requested buffers */
         struct em28xx_buffer            *buf;
 
-                /* Store last filled frame */
-        int                             last_field;
-
                 /* Stores the number of received fields */
         int                             nfields;
 };