Return immediately if the target number of buffers is the same as
the current one and memory access type doesn't change.
Signed-off-by: NMarek Szyprowski <m.szyprowski@samsung.com>
Signed-off-by: NKyungmin Park <kyungmin.park@samsung.com>
Signed-off-by: NMauro Carvalho Chehab <mchehab@redhat.com>

This patch fixes 2 minor bugs in videobuf2 core:
1. Queue should be reallocated if one change the memory access
method without changing the number of buffers.
2. In case of REQBUFS(0), the request should not be passed to the
driver.
Signed-off-by: NMarek Szyprowski <m.szyprowski@samsung.com>
Signed-off-by: NKyungmin Park <kyungmin.park@samsung.com>
Signed-off-by: NMauro Carvalho Chehab <mchehab@redhat.com>

drivers/media/video/videobuf2-core.c: In function ‘__vb2_perform_fileio’:
drivers/media/video/videobuf2-core.c:1638: warning: format ‘%ld’ expects type ‘long int’, but argument 4 has type ‘size_t’
drivers/media/video/videobuf2-core.c:1697: warning: format ‘%ld’ expects type ‘long int’, but argument 2 has type ‘size_t’
drivers/media/video/videobuf2-core.c:1703: warning: format ‘%ld’ expects type ‘long int’, but argument 2 has type ‘size_t’
Signed-off-by: NMauro Carvalho Chehab <mchehab@redhat.com>

Add a generic file io (read and write) emulator for videobuf2. It uses
MMAP memory type buffers and generic vb2 calls: req_bufs, qbuf and
dqbuf. Video date is being copied from mmap buffers to userspace with
standard copy_to_user() function. To add support for file io the driver
needs to provide an additional callback - read_setup or write_setup. It
should provide the default number of buffers used by emulator and flags.

With these flags one can detemine the style of read() or write()
emulation. By default 'streaming' style is used. With
VB2_FILEIO_READ_ONCE flag one can select 'one shot' mode for read()
emulator. With VB2_FILEIO_WRITE_IMMEDIATE flag one can select immediate
conversion of write calls to qbuf for write() emulator, so the vb2 will
not wait until each buffer is filled completely before queueing it to
the driver.
Signed-off-by: NMarek Szyprowski <m.szyprowski@samsung.com>
Signed-off-by: NKyungmin Park <kyungmin.park@samsung.com>
CC: Pawel Osciak <pawel@osciak.com>
Reviewed-by: NHans Verkuil <hverkuil@xs4all.nl>
Signed-off-by: NMauro Carvalho Chehab <mchehab@redhat.com>

Videobuf2 is a Video for Linux 2 API-compatible driver framework for
multimedia devices. It acts as an intermediate layer between userspace
applications and device drivers. It also provides low-level, modular
memory management functions for drivers.

Videobuf2 eases driver development, reduces drivers' code size and aids in
proper and consistent implementation of V4L2 API in drivers.

Videobuf2 memory management backend is fully modular. This allows custom
memory management routines for devices and platforms with non-standard
memory management requirements to be plugged in, without changing the
high-level buffer management functions and API.

The framework provides:
- implementations of streaming I/O V4L2 ioctls and file operations
- high-level video buffer, video queue and state management functions
- video buffer memory allocation and management
Signed-off-by: NPawel Osciak <p.osciak@samsung.com>
Signed-off-by: NMarek Szyprowski <m.szyprowski@samsung.com>
Signed-off-by: NKyungmin Park <kyungmin.park@samsung.com>
CC: Pawel Osciak <pawel@osciak.com>
Reviewed-by: NHans Verkuil <hverkuil@xs4all.nl>
Signed-off-by: NMauro Carvalho Chehab <mchehab@redhat.com>