V4L/DVB (13908): cx18: Add initial working VIDIOC_G_ENC_INDEX ioctl() support

VIDIOC_G_ENC_INDEX support see the light of day.
Some notes:
1. With default capture parameters, the CX23418 seems to transfer 192 index
entries (4.5 kB worth) at 10 second intervals.

2. Index streams don't seem to be supported for MPEG 2 TS streams

3. The index entries seem to claim every frame is a B-Frame.  Possible
firmware bug.

4. The cx18 driver does not try to capture an index stream when inserting
sliced VBI into the MPEg stream as the offsets would need fixup.

Signed-off-by: Andy Walls <awalls@radix.net>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>

1 files changed, 12 insertions, 0 deletions

diff --git a/drivers/media/video/cx18/cx18-driver.h b/drivers/media/video/cx18/cx18-driver.h
index ff3426206765..930bab647467 100644
--- a/drivers/media/video/cx18/cx18-driver.h
+++ b/drivers/media/video/cx18/cx18-driver.h
@@ -288,6 +288,18 @@ struct cx18_options {
 #define CX18_SLICED_TYPE_WSS_625        (5)
 #define CX18_SLICED_TYPE_VPS            (7)
 
+/**
+ * list_entry_is_past_end - check if a previous loop cursor is off list end
+ * @pos:        the type * previously used as a loop cursor.
+ * @head:       the head for your list.
+ * @member:     the name of the list_struct within the struct.
+ *
+ * Check if the entry's list_head is the head of the list, thus it's not a
+ * real entry but was the loop cursor that walked past the end
+ */
+#define list_entry_is_past_end(pos, head, member) \
+        (&pos->member == (head))
+
 struct cx18_buffer {
         struct list_head list;
         dma_addr_t dma_handle;