As video hardware pipelines become increasingly complex and
configurable, the current hardware description through v4l2 subdevices
reaches its limits. In addition to enumerating and configuring
subdevices, video camera drivers need a way to discover and modify at
runtime how those subdevices are connected. This is done through new
elements called entities, pads and links.
An entity is a basic media hardware building block. It can correspond to
a large variety of logical blocks such as physical hardware devices
(CMOS sensor for instance), logical hardware devices (a building block
in a System-on-Chip image processing pipeline), DMA channels or physical
connectors.
A pad is a connection endpoint through which an entity can interact with
other entities. Data (not restricted to video) produced by an entity
flows from the entity's output to one or more entity inputs. Pads should
not be confused with physical pins at chip boundaries.
A link is a point-to-point oriented connection between two pads, either
on the same entity or on different entities. Data flows from a source
pad to a sink pad.
Links are stored in the source entity. To make backwards graph walk
faster, a copy of all links is also stored in the sink entity. The copy
is known as a backlink and is only used to help graph traversal.
The entity API is made of three functions:
- media_entity_init() initializes an entity. The caller must provide an
array of pads as well as an estimated number of links. The links array
is allocated dynamically and will be reallocated if it grows beyond the
initial estimate.
- media_entity_cleanup() frees resources allocated for an entity. It
must be called during the cleanup phase after unregistering the entity
and before freeing it.
- media_entity_create_link() creates a link between two entities. An
entry in the link array of each entity is allocated and stores pointers
to source and sink pads.
When a media device is unregistered, all its entities are unregistered
automatically.
The code is based on Hans Verkuil <hverkuil@xs4all.nl> initial work.
Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Sakari Ailus <sakari.ailus@iki.fi>
Acked-by: Hans Verkuil <hverkuil@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>
The media_device structure abstracts functions common to all kind of
media devices (v4l2, dvb, alsa, ...). It manages media entities and
offers a userspace API to discover and configure the media device
internal topology.
Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Acked-by: Hans Verkuil <hverkuil@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>
The media_devnode structure provides support for registering and
unregistering character devices using a dynamic major number. Reference
counting is handled internally, making device drivers easier to write
without having to solve the open/disconnect race condition issue over
and over again.
The code is based on video/v4l2-dev.c.
[mchehab@redhat.com: Remove linux/smp_lock.h include to not break compilation on bisect]
Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Acked-by: Hans Verkuil <hverkuil@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>
This is the first step of creating a common code for IR that can be
used by other input devices.
For now, keep IR dir at drivers/media, to easy the movement of the IR files,
but later patches may move it to drivers/IR or drivers/input/IR.
No functional changes is done on this patch.
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>
After commit 039d40019f
(V4L/DVB (7898): Fix VIDEO_MEDIA Kconfig logic)
VIDEO_MEDIA is no longer usable in Makefile's for deciding
which directories we enter, resulting in compile errors like the
following with CONFIG_VIDEO_DEV=y, CONFIG_DVB_CORE=m:
<-- snip -->
...
MODPOST 187 modules
...
make[2]: *** [__modpost] Error 1
<-- snip -->
The easiest solution is to always enter video/
Signed-off-by: Adrian Bunk <bunk@kernel.org>
Acked-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Mauro Carvalho Chehab <mchehab@infradead.org>
Fix allmodconfig build bug introduced in latest -git by commit
7c91f0624a ("V4L/DVB(7767): Move tuners to common/tuners"):
LD kernel/built-in.o
LD drivers/built-in.o
ld: drivers/media/built-in.o: No such file: No such file or directory
which happens if all media drivers are modular:
http://redhat.com/~mingo/misc/config-Wed_Apr_30_09_24_48_CEST_2008.bad
In that case there's no obj-y rule connecting all the built-in.o files and
the link tree breaks.
The fix is to add a guaranteed obj-y rule for the core vmlinux to build.
(which results in an empty object file if all media drivers are modular)
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Acked-by: Sam Ravnborg <sam@ravnborg.org>
Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
There were several issues in the past, caused by the hybrid tuner design, since
now, the same tuner can be used by drivers/media/dvb and drivers/media/video.
Kconfig items were rearranged, to split V4L/DVB core from their drivers.
Signed-off-by: Mauro Carvalho Chehab <mchehab@infradead.org>
Since not all code under drivers/media/video/ depends on
CONFIG_VIDEO_DEV we cannot only enter it depending
on CONFIG_VIDEO_DEV.
Signed-off-by: Adrian Bunk <bunk@kernel.org>
Signed-off-by: Mauro Carvalho Chehab <mchehab@infradead.org>
Change Kconfig objects from "menu, config" into "menuconfig" so
that the user can disable the whole feature without having to
enter the menu first.
Also remove one indirection (CONFIG_DVB) that does not seem to
be really used inside the kernel.
Signed-off-by: Jan Engelhardt <jengelh@gmx.de>
Signed-off-by: Mauro Carvalho Chehab <mchehab@infradead.org>
Don't build empty built-in.o when DVB/V4L is not configured. Thanks to Sam
Ravnborg and Keith Owens.
Signed-off-by: Johannes Stezenbach <js@linuxtv.org>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Initial git repository build. I'm not bothering with the full history,
even though we have it. We can create a separate "historical" git
archive of that later if we want to, and in the meantime it's about
3.2GB when imported into git - space that would just make the early
git days unnecessarily complicated, when we don't have a lot of good
infrastructure for it.
Let it rip!
Laurent Pinchart