videobuf-dma-contig: zero copy USERPTR support

Since videobuf-dma-contig is designed to handle physically contiguous
memory, this patch modifies the videobuf-dma-contig code to only accept a
user space pointer to physically contiguous memory.  For now only
VM_PFNMAP vmas are supported, so forget hotplug.

On SuperH Mobile we use this with our sh_mobile_ceu_camera driver together
with various multimedia accelerator blocks that are exported to user space
using UIO.  The UIO kernel code exports physically contiguous memory to
user space and lets the user space application mmap() this memory and pass
a pointer using the USERPTR interface for V4L2 zero copy operation.

With this approach we support zero copy capture, hardware scaling and
various forms of hardware encoding and decoding.

[[email protected]: coding-style fixes]
Signed-off-by: Magnus Damm <[email protected]>
Cc: Johannes Weiner <[email protected]>
Cc: Paul Mundt <[email protected]>
Acked-by: Mauro Carvalho Chehab <[email protected]>
Cc: Hans Verkuil <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>

0 files changed, 0 insertions, 0 deletions