videobuf-dma-contig: zero copy USERPTR support
commit720b17e759a50635c429ccaa2ec3d01edb4f92d6
authorMagnus Damm <damm@igel.co.jp>
Tue, 16 Jun 2009 22:32:36 +0000 (16 15:32 -0700)
committerLinus Torvalds <torvalds@linux-foundation.org>
Wed, 17 Jun 2009 02:47:40 +0000 (16 19:47 -0700)
tree8f6d86a05b328a54bd312b62e1fbc844c1dc30ba
parent3b6748e2dd69906af3835db4dc9d1c8a3ee4c68c
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.

[akpm@linux-foundation.org: coding-style fixes]
Signed-off-by: Magnus Damm <damm@igel.co.jp>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Paul Mundt <lethal@linux-sh.org>
Acked-by: Mauro Carvalho Chehab <mchehab@infradead.org>
Cc: Hans Verkuil <hverkuil@xs4all.nl>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
drivers/media/video/videobuf-dma-contig.c