Explain when the V4L2_CTRL_FLAG_MODIFY_LAYOUT and
V4L2_CTRL_FLAG_MODIFY_GRABBER flags should be used.
Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
Acked-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>
The metadata buffer type is used to transfer metadata between userspace
and kernelspace through a V4L2 buffers queue. It comes with a new
metadata capture capability and format description.
Signed-off-by: Laurent Pinchart <laurent.pinchart+renesas@ideasonboard.com>
Tested-by: Guennadi Liakhovetski <guennadi.liakhovetski@intel.com>
Acked-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Acked-by: Hans Verkuil <hans.verkuil@cisco.com>
[hans.verkuil@cisco.com: removed left-over 'experimental' note]
[hans.verkuil@cisco.com: add newline after _v4l2-meta-format label]
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>
V4L2 exposes parameters that influence buffers sizes through the format
ioctls (VIDIOC_G_FMT, VIDIOC_TRY_FMT, VIDIOC_S_FMT, and possibly
VIDIOC_G_SELECTION and VIDIOC_S_SELECTION). Other parameters not part of
the format structure may also influence buffer sizes or buffer layout in
general. One existing such parameter is rotation, which is implemented
by the V4L2_CID_ROTATE control and thus exposed through the V4L2 control
ioctls.
The interaction between those parameters and buffers is currently only
partially specified by the V4L2 API. In particular interactions between
controls and buffers isn't specified at all. The behaviour of the
VIDIOC_S_FMT and VIDIOC_S_SELECTION ioctls when buffers are allocated is
also not fully specified.
This patch clearly defines and documents the interactions between
formats, selections, controls and buffers.
The preparatory discussions for the documentation change considered
completely disallowing controls that change the buffer size or layout,
in favour of extending the format API with a new ioctl that would bundle
those controls with format information. The idea has been rejected, as
this would essentially be a restricted version of the upcoming request
API that wouldn't bring any additional value.
Another option we have considered was to mandate the use of the request
API to modify controls that influence buffer size or layout. This has
also been rejected on the grounds that requiring the request API to
change rotation even when streaming is stopped would significantly
complicate implementation of drivers and usage of the V4L2 API for
applications.
Applications will however be required to use the upcoming request API to
change at runtime formats or controls that influence the buffer size or
layout, because of the need to synchronize buffers with the formats and
controls. Otherwise there would be no way to interpret the content of a
buffer correctly.
Signed-off-by: Laurent Pinchart <laurent.pinchart+renesas@ideasonboard.com>
Acked-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Acked-by: Hans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>
There are several broken references there, due to the conversion to
C domain. Fix them using this shell script and manually adjust what's
broken:
# funcs is a file with the broken functions/references
for i in $(cat funcs|sort|uniq|perl -ne 'print "$1\n" if (m/(\S+)$/)'); do
i=${i//-/_}
echo $i
j=${i//_/-}
for k in $(git grep -l "_$j:" Documentation/); do
sed s,\_$j\:,"c\:type\:\: $i", <$k >a && mv a $k
done
for k in $(git grep -l "$j" Documentation/media/*.exceptions); do
sed s,$j,":c\:type\:\`$i\`", <$k >a && mv a $k
done
for k in $(git grep -l "$j" Documentation/); do
sed "s,:ref:\`$i <$j>\`,:c:type:\`$i\`," <$k >a && mv a $k
sed "s,:ref:\`$j\`,:c:type:\`$i\`," <$k >a && mv a $k
sed -E "s,:ref:\`(.*)<$j>\`,:c:type:\`\1<$i>\`," <$k >a && mv a $k
done
for k in $(git grep -l "<$j>" include/media); do
sed -E "s,:ref:\`(.*)<$j>\`,enum \&$i," <$k >a && mv a $k
done
done
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>
Fix those warnings:
Documentation/media/uapi/cec/cec-ioc-dqevent.rst:124: WARNING: c:func reference target not found: clock_gettime(2)
By replacing it with the right function name, using this shell script:
for i in `find Documentation/media -type f`; do sed 's,clock_gettime(2),clock_gettime,' <$i >a && mv a $i; done
Please notice that this will make the nitpick mode to shut up
complaining about that, becasue clock_gettime is on its exclude list,
but the cross reference will be undefined until someone documents
this function at the core documentation.
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>
The :c:type: references point to the structure name, and not to
struct foo.
Fixed via this shell script:
for i in `find Documentation/media -type f`; do perl -ne 'if (s/\:c\:type\:\`struct\s*(\S+)\`/struct :c:type:`$1`/) { s/struct\s+struct/struct/; s/(struct\s+\:c\:type\:\`\S+\`)\s+structure/$1/; } print $_' <$i >a && mv a $i; done
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>
Instead of using c:type:`struct foo <foo>`, use:
struct c:type:`foo`
This patch was generated via this shell script:
for i in `find Documentation/media -type f`; do perl -ne 'if (m/\:c\:type\:\`struct\s+(\S+)\s*\<(\S+)\>\`/) { $s=$1; $r=$2; if ($s eq $r) { s/\:c\:type\:\`struct\s+(\S+)\s*\<(\S+)\>\`/struct :c:type:`$2`/; s/struct\s+struct/struct/; s/(struct\s+\:c\:type\:\`\S+\`)\s+structure/$1/; }} print $_' <$i >a && mv a $i; done
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>
instead of declaring the uAPI structs using usual refs, e. g.:
.. _foo-struct:
Use the C domain way:
.. c:type:: foo_struct
This way, the kAPI documentation can use cross-references to
point to the uAPI symbols.
That solves about ~100 undefined warnings like:
WARNING: c:type reference target not found: foo_struct
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>
The table columns are not properly displayed. Also, some
tables are too big to fit into just one page. So, fix them,
in order to better display the tables.
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>
LaTeX doesn't handle too well auto-width on tables, and ReST
markup requires an special tag to give it the needed hints.
As we're using A4 paper, we have 17cm of useful spaces. As
most media tables have widths, let's use it to generate the
needed via the following perl script:
my ($line_size, $table_header, $has_cols) = (17.5, 0, 0);
my $out;
my $header = "";
my @widths = ();
sub round { $_[0] > 0 ? int($_[0] + .5) : -int(-$_[0] + .5) }
while (<>) {
if (!$table_header) {
$has_cols = 1 if (m/..\s+tabularcolumns::/);
if (m/..\s+flat-table::/) {
$table_header = 1;
$header = $_;
next;
}
$out .= $_;
next;
}
$header .= $_;
@widths = split(/ /, $1) if (m/:widths:\s+(.*)/);
if (m/^\n$/) {
if (!$has_cols && @widths) {
my ($tot, $t, $i) = (0, 0, 0);
foreach my $v(@widths) { $tot += $v; };
$out .= ".. tabularcolumns:: |";
for ($i = 0; $i < scalar @widths - 1; $i++) {
my $v = $widths[$i];
my $w = round(10 * ($v * $line_size) / $tot) / 10;
$out .= sprintf "p{%.1fcm}|", $w;
$t += $w;
}
my $w = $line_size - $t;
$out .= sprintf "p{%.1fcm}|\n\n", $w;
}
$out .= $header;
$table_header = 0;
$has_cols = 0;
$header = "";
@widths = ();
}
}
print $out;
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>
Change multi-line note tags to be more symetric, e. g. not starting
the text together witht the tag.
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>
This patch touches on places where it shouldn't: image
files and code examples. Also, it doesn't fix all array
occurrences.
So, let's revert it.
This reverts commit ffbab694ed.
Those characters are used for citations. Better to escape, to
avoid them to be misinterpreted.
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>
Fix it by adding a header to the flat-table to match to
the list of define symbols.
As a side-effect, it also removes some exceptions from
videodev2.h.rst.
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>
There are several notes and warning mesages in the middle of
the media docbook. Use the ReST tags for that, as it makes
them visually better and hightlights them.
While here, modify a few ones to make them clearer.
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>
The name of the subsystem is "media", and not "linux_tv". Also,
as we plan to add other stuff there in the future, let's
rename also the media uAPI book to media_uapi, to make it
clearer.
No functional changes.
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>
