[media] v4l2-event: add optional merge and replace callbacks

When the event queue for a subscribed event is full, then the oldest
event is dropped. It would be nice if the contents of that oldest
event could be merged with the next-oldest. That way no information is
lost, only intermediate steps are lost.

This patch adds optional replace() (called when only one kevent was allocated)
and merge() (called when more than one kevent was allocated) callbacks that
will be called to do this job.

These two callbacks are implemented for the V4L2_EVENT_CTRL event.

Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>
[media] v4l2-ctrls: don't initially set CH_VALUE for write-only controls

When sending the SEND_INITIAL event for write-only controls the
V4L2_EVENT_CTRL_CH_VALUE flag should not be set. It's meaningless.

Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>
[media] v4l2-ctrls: improve discovery of controls of the same cluster

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 <hans.verkuil@cisco.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>
[media] v4l2-ctrls: split try_or_set_ext_ctrls()

Split try_or_set_ext_ctrls() into a validate_ctrls() part ('Phase 1')
and merge the second part ('Phase 2') into try_set_ext_ctrls().

This makes a lot more sense and it also does the validation before
trying to try/set the controls.

Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>
[media] v4l2-ctrls: v4l2_ctrl_handler_setup code simplification

Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>
[media] v4l2-framework.txt: updated v4l2_fh_init documentation

v4l2_fh_init now returns void instead of int, updated the doc.

Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>
[media] v4l2-framework.txt: update v4l2_event section

Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>
[media] DocBook: update V4L Event Interface section

Starting with v3.1 the V4L2 API provides certain guarantees with respect to
events. Document these.

Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>
[media] v4l2-ctrls/v4l2-events: small coding style cleanups

Thanks to Laurent Pinchart <laurent.pinchart@ideasonboard.com>.

Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>
[media] v4l2-event.h: add overview documentation to the header

It's getting confusing who is linking to what, so add an overview at
the start of the header.

Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>
[media] v4l2-ctrls.c: add support for V4L2_EVENT_SUB_FL_ALLOW_FEEDBACK

Normally no control events will go to the filehandle that called the
VIDIOC_S_CTRL/VIDIOC_S_EXT_CTRLS ioctls. This is to prevent a feedback
loop.

This can now be overridden by setting the new V4L2_EVENT_SUB_FL_ALLOW_FEEDBACK
flag.

Based on suggestions from Mauro Carvalho Chehab <mchehab@redhat.com> and
Laurent Pinchart <laurent.pinchart@ideasonboard.com>.

Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>
[media] marvell-cam: Working s/g DMA

The core Marvell camera driver can now do scatter/gather DMA on controllers
which support that functionality.

Signed-off-by: Jonathan Corbet <corbet@lwn.net>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>
[media] marvell-cam: use S/G DMA by default

Scatter/gather DMA mode works nicely on this platform and is clearly the
best way of doing things.

Signed-off-by: Jonathan Corbet <corbet@lwn.net>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>
[media] DocBook/media-ioc-setup-link.xml: Remove EBUSY

The EBUSY is already described as a generic error condition, with a
similar text.

Acked-by: Hans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>
[media] DocBook: Add an error code session for LIRC interface

Acked-by: Hans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>
[media] DocBook: Add return error codes to LIRC ioctl session

Add a reference for the generic error code chapter to LIRC ioctl
description.

Acked-by: Hans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>
[media] siano: bad parameter is -EINVAL and not -EFAULT

Acked-by: Hans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>
[media] nxt6000: i2c bus error should return -EIO

data from/to userspace. Don't mix it with I2C bus error (-EIO).

Acked-by: Hans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>
[media] dvb-bt8xx: Don't return -EFAULT when a device is not found

When a device (or their PCI structs) are not found, the error should
be -ENODEV. -EFAULT is reserved for errors while copying arguments
from/to userspace.

Acked-by: Hans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>
[media] return -ENOTTY for unsupported ioctl's at legacy drivers

Those drivers are not relying at the V4L2 core to handle the ioctl's.
So, we need to manually patch them every time a change goes to the
core.

Acked-by: Hans Verkuil <hans.verkuil@cisco.com>
Acked-By: Mike Isely <isely@pobox.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>