Make vivi driver to use vmalloced pointers

From: Mauro Carvalho Chehab <mchehab@infradead.org>

Before this patch, vivi were simulating a scatter gather DMA transfer.
While this is academic, showing how stuff really works on a real PCI 
device, this means a non-optimized code. 

There are only two memory models that vivi implements:

	1) kernel alloced memory. This is also used by read() method.
	   On this case, a vmalloc32 buffer is allocated at kernel;

	2) userspace allocated memory. This is used by most userspace apps.
	   video-buf will store this pointer.
	   a simple copy_to_user is enough to transfer data.

The third memory model scenario supported by video-buf is overlay mode. 
This model is not implemented on vivi and unlikely to be implemented on 
newer drivers, since now, most userspace apps do some post-processing 
(like de-interlacing).

After this patch, some cleanups may be done at video-buf.c to avoid 
allocating pages, when the driver doesn't need a PCI buffer. This is the 
case of vivi and usb drivers.

Signed-off-by: Mauro Carvalho Chehab <mchehab@infradead.org>

1 files changed, 3 insertions, 0 deletions

diff --git a/linux/include/media/video-buf.h b/linux/include/media/video-buf.h
index ae694cfbc..cb216d0ab 100644
--- a/linux/include/media/video-buf.h
+++ b/linux/include/media/video-buf.h
@@ -78,6 +78,9 @@ struct videobuf_dmabuf {
 	/* for kernel buffers */
 	void                *vmalloc;
 
+	/* Stores the userspace pointer to vmalloc area */
+	void                *varea;
+
 	/* for overlay buffers (pci-pci dma) */
 	dma_addr_t          bus_addr;