[media] videobuf2-core: fix plane_sizes handling in VIDIOC_CREATE_BUFS

The handling of q->plane_sizes was wrong in vb2_core_create_bufs().
The q->plane_sizes array was global and it was overwritten by create_bufs.
So if reqbufs was called with e.g. size 100000 then q->plane_sizes[0] would
be set to 100000. If create_bufs was called afterwards with size 200000,
then q->plane_sizes[0] would be overwritten with the new value. Calling
create_bufs again for size 100000 would cause an error since 100000 is now
less than q->plane_sizes[0].

This patch fixes this problem by 1) removing q->plane_sizes and using the
vb->planes[].length field instead, and 2) by introducing a min_length field
in struct vb2_plane. This field is set to the plane size as returned by
the queue_setup op and is the minimum required plane size. So user pointers
or dmabufs should all be at least this size.

Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
Reported-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@osg.samsung.com>
diff --git a/include/media/videobuf2-core.h b/include/media/videobuf2-core.h
index b88dbba..ef03ae5 100644
--- a/include/media/videobuf2-core.h
+++ b/include/media/videobuf2-core.h
@@ -129,6 +129,8 @@
  * @dbuf_mapped:	flag to show whether dbuf is mapped or not
  * @bytesused:	number of bytes occupied by data in the plane (payload)
  * @length:	size of this plane (NOT the payload) in bytes
+ * @min_length:	minimum required size of this plane (NOT the payload) in bytes.
+ *		@length is always greater or equal to @min_length.
  * @offset:	when memory in the associated struct vb2_buffer is
  *		VB2_MEMORY_MMAP, equals the offset from the start of
  *		the device memory for this plane (or is a "cookie" that
@@ -150,6 +152,7 @@
 	unsigned int		dbuf_mapped;
 	unsigned int		bytesused;
 	unsigned int		length;
+	unsigned int		min_length;
 	union {
 		unsigned int	offset;
 		unsigned long	userptr;
@@ -489,7 +492,6 @@
 	wait_queue_head_t		done_wq;
 
 	void				*alloc_ctx[VB2_MAX_PLANES];
-	unsigned int			plane_sizes[VB2_MAX_PLANES];
 
 	unsigned int			streaming:1;
 	unsigned int			start_streaming_called:1;