linux-toradex.git/include/media/v4l2-ctrls.h, branch v3.4.16

Merge tag 'device-for-3.4' of git://git.kernel.org/pub/scm/linux/kernel/git/paulg/linux

2012-03-24T17:41:37+00:00

Pull  avoidance patches from Paul Gortmaker:
 "Nearly every subsystem has some kind of header with a proto like:

	void foo(struct device *dev);

  and yet there is no reason for most of these guys to care about the
  sub fields within the device struct.  This allows us to significantly
  reduce the scope of headers including headers.  For this instance, a
  reduction of about 40% is achieved by replacing the include with the
  simple fact that the device is some kind of a struct.

  Unlike the much larger module.h cleanup, this one is simply two
  commits.  One to fix the implicit  users, and then one
  to delete the device.h includes from the linux/include/ dir wherever
  possible."

* tag 'device-for-3.4' of git://git.kernel.org/pub/scm/linux/kernel/git/paulg/linux:
  device.h: audit and cleanup users in main include dir
  device.h: cleanup users outside of linux/include (C files)

device.h: audit and cleanup users in main include dir

2012-03-16T14:38:24+00:00

The  header includes a lot of stuff, and
it in turn gets a lot of use just for the basic "struct device"
which appears so often.

Clean up the users as follows:

1) For those headers only needing "struct device" as a pointer
in fcn args, replace the include with exactly that.

2) For headers not really using anything from device.h, simply
delete the include altogether.

3) For headers relying on getting device.h implicitly before
being included themselves, now explicitly include device.h

4) For files in which doing #1 or #2 uncovers an implicit
dependency on some other header, fix by explicitly adding
the required header(s).

Any C files that were implicitly relying on device.h to be
present have already been dealt with in advance.

Total removals from #1 and #2: 51.  Total additions coming
from #3: 9.  Total other implicit dependencies from #4: 7.

As of 3.3-rc1, there were 110, so a net removal of 42 gives
about a 38% reduction in device.h presence in include/*

Signed-off-by: Paul Gortmaker

[media] v4l2-ctrls: add helper functions for control events

2012-02-14T18:38:43+00:00

Many drivers just support control events, and most radio drivers just need
to poll for control events. Add some functions to simplify those jobs.

Signed-off-by: Hans Verkuil 
Signed-off-by: Mauro Carvalho Chehab

[media] v4l2: standardize log start/end message

2012-02-14T18:38:13+00:00

For drivers that properly use the v4l2 framework (i.e. set v4l2_dev in the
video_device struct), the start and end messages of VIDIOC_LOG_STATUS are
now generated automatically. People tended to forget these, but the v4l2-ctl
tool scans for these messages, and it also makes it easier to read the status
output in the kernel log.

The cx18, ivtv and bttv drivers were changed since they no longer need to
log these start/end messages.

In saa7164 two empty log_status functions were removed.

Also added a helper function to v4l2-ctrl.c that can be used as the
vidioc_log_status callback if all you need to do is to log the current control
values. This is now used by pwc and vivi.

Signed-off-by: Hans Verkuil 
Cc: Steven Toth 
Cc: Andy Walls 
Cc: Hans de Goede 
Signed-off-by: Mauro Carvalho Chehab

[media] v4l2-ctrls: implement new volatile autocluster scheme

2011-09-21T13:48:30+00:00

The problem tackled in this patch is how to handle volatile autoclusters
correctly. A volatile autocluster is a cluster of related controls where one
control is the control that toggles between manual and auto mode and the other
controls are the values for the manual mode. For example autogain and gain,
autoexposure and exposure, etc.

If the hardware lets you read out the automatically calculated manual values
while in automode, then those manual controls should be marked volatile.

gain value as calculated by the autogain circuitry, then you would mark the
gain control as volatile (i.e. continuously changing).

The question in such use cases is what to do when switching from the auto
mode to the manual mode. Should we switch to the last set manual values or
should the volatile values be copied and used as the initial manual values.

For example: suppose the mode is manual gain and gain is set to 5. Then
autogain is turned on and the gain is set by the hardware to 2. Finally
the user switches back to manual gain. What should the gain be? 2 or 5?

After a long discussion the decisions was made to keep the last value as
calculated by the auto mode (so 2 in the example above).

The reason is that webcams that do such things will adapt themselves to
the current light conditions and when you switch back to manual mode you
expect that you keep the same picture. If you would switch back to old
manual values, then that would give you a suddenly different picture,
which is jarring for the user.

Additionally, this would be difficult to implement in applications that
store and restore the control values at application exit and start.

If you want to keep the old manual values when you switch from auto to
manual, then there would have to be a way for applications to get hold
of those old values while in auto mode, but there isn't.

So this patch will do all the heavy lifting in v4l2-ctrls.c: if you go
from auto mode to manual mode and the manual controls are volatile, then
g_volatile_ctrl will be called to get the current values for the manual
controls before switching to manual mode.

Signed-off-by: Hans Verkuil 
Acked-by: Hans de Goede 
Signed-off-by: Mauro Carvalho Chehab

[media] v4l2-ctrls: replace is_volatile with V4L2_CTRL_FLAG_VOLATILE

2011-09-21T12:52:21+00:00

With the new flag there is no need anymore to have a separate is_volatile
field. Modify all users to use the new flag.

Signed-off-by: Hans Verkuil 
Acked-by: Hans de Goede 
Signed-off-by: Mauro Carvalho Chehab

[media] v4l2-ctrls/v4l2-events: small coding style cleanups

2011-07-27T20:53:34+00:00

Thanks to Laurent Pinchart .

Signed-off-by: Hans Verkuil 
Signed-off-by: Mauro Carvalho Chehab

[media] v4l2-ctrls: improve discovery of controls of the same cluster

2011-07-27T20:53:31+00:00

The implementation of VIDIOC_G/S/TRY_EXT_CTRLS in the control framework has
to figure out which controls in the control list belong to the same cluster.
Since controls belonging to the same cluster need to be handled as a unit,
this is important information.

It did that by going over the controls in the list and for each control that
belonged to a multi-control cluster it would walk the remainder of the list
to try and find controls that belong to that same cluster.

This approach has two disadvantages:

1) it was a potentially quadratic algorithm (although highly unlikely that
it would ever be that bad in practice).
2) it took place with the control handler's lock held.

Since we want to make it possible in the future to change control values
from interrupt context, doing a lot of work while holding a lock is not a
good idea.

In the new code the algorithm is no longer quadratic but linear in the
number of controls in the list. Also, it now can be done beforehand.

Another change that was made was to so the try and set at the same time.
Before when S_TRY_EXT_CTRLS was called it would 'try' the controls first,
and then it would 'set' them. The idea was that any 'try' errors would
prevent the 'set' from happening, thus avoiding having partially set
control lists.

However, this caused more problems than it solved because between the 'try'
and the 'set' changes might have happened, so it had to try a second time,
and since actual controls with a try_ctrl op are very rare (and those that
we have just adjust values and do not return an error), I've decided to
drop that two-stage approach and just combine try and set.

Signed-off-by: Hans Verkuil 
Signed-off-by: Mauro Carvalho Chehab

[media] v4l2-event/ctrls/fh: allocate events per fh and per type instead of just per-fh

2011-07-27T20:53:31+00:00

The driver had to decide how many events to allocate when the v4l2_fh struct
was created. It was possible to add more events afterwards, but there was no
way to ensure that you wouldn't miss important events if the event queue
would fill up for that filehandle.

In addition, once there were no more free events, any new events were simply
dropped on the floor.

For the control event in particular this made life very difficult since
control status/value changes could just be missed if the number of allocated
events and the speed at which the application read events was too low to keep
up with the number of generated events. The application would have no idea
what the latest state was for a control since it could have missed the latest
control change.

So this patch makes some major changes in how events are allocated. Instead
of allocating events per-filehandle they are now allocated when subscribing an
event. So for that particular event type N events (determined by the driver)
are allocated. Those events are reserved for that particular event type.
This ensures that you will not miss events for a particular type altogether.

In addition, if there are N events in use and a new event is raised, then
the oldest event is dropped and the new one is added. So the latest event
is always available.

This can be further improved by adding the ability to merge the state of
two events together, ensuring that no data is lost at all. This will be
added in the next patch.

This also makes it possible to allow the user to determine the number of
events that will be allocated. This is not implemented at the moment, but
would be trivial.

Signed-off-by: Hans Verkuil 
Signed-off-by: Mauro Carvalho Chehab

[media] v4l2-ctrls/event: remove struct v4l2_ctrl_fh, instead use v4l2_subscribed_event

2011-07-27T20:53:31+00:00

The v4l2_ctrl_fh struct connected v4l2_ctrl with v4l2_fh so the control
would know which filehandles subscribed to it. However, it is much easier
to use struct v4l2_subscribed_event directly for that and get rid of that
intermediate struct.

Signed-off-by: Hans Verkuil 
Signed-off-by: Mauro Carvalho Chehab