media: videobuf2: fix buffer management issues

Use right buffer flag NVMAP_HANDLE_WRITE_COMBINE to allocate buffer,
which can be shared by VI/CSI and CPU. Don't use NVMAP_HEAP_SYSMEM.
It is validated to old T20 silicon and can't support big buffers. By
default, our nvmap_alloc() will use IOVMM to allocate buffers.

nvmap_pin() gives us IOVA for hardware engines like VI/CSI module
with IOMMU enabled in kernel. nvmap_mmap() gives us VA for CPU
read/write operations. So we need to convert VA address to physical
address of the buffer and map that buffer to user space processor's
memory space "page by page".

Change-Id: I543d9d95fc14395200647e09480f25d9bc001e00
Signed-off-by: Bryan Wu <pengw@nvidia.com>

0 files changed, 0 insertions, 0 deletions