Hi Sylwester On Wed, 27 Jul 2011, Sylwester Nawrocki wrote: > Hi Gueannadi, > > On 07/20/2011 10:43 AM, Guennadi Liakhovetski wrote: > > A possibility to preallocate and initialise buffers of different sizes > > in V4L2 is required for an efficient implementation of asnapshot mode. > > This patch adds two new ioctl()s: VIDIOC_CREATE_BUFS and > > VIDIOC_PREPARE_BUF and defines respective data structures. > > > > Signed-off-by: Guennadi Liakhovetski <g.liakhovetski@xxxxxx> > > --- > > > > It's been almost a month since v2, the only comments were a request to > > increase the reserved space in the new ioctl() and to improve > > documentation. The reserved field is increased in this version, > > documentation also has been improved in multiple locations. I think, > > documentation can be further improved at any time, but if there are no > > objections against the actual contents of this patch, maybe we can commit > > this version. I still don't see v3.0;-), so, maybe we even can push it for > > 3.1. A trivial comparison with v2 shows the size of the reserved field as > > the only change in the API, and the compatibility fix as the only two > > functional changes. > > > > v3: addressed multiple comments by Sakari Ailus > > > > 1. increased reserved field in "struct v4l2_create_buffers" to 8 32-bit > > ints > > 2. multiple documentation fixes and improvements > > 3. fixed misplaced "case VIDIOC_PREPARE_BUF" in ioctl 32-bit compatibility > > processing > > > > v2: > > > > 1. add preliminary Documentation > > 2. add flag V4L2_BUFFER_FLAG_NO_CACHE_CLEAN > > 3. remove VIDIOC_DESTROY_BUFS > > 4. rename SUBMIT to VIDIOC_PREPARE_BUF > > 5. add reserved field to struct v4l2_create_buffers > > 6. cache handling flags moved to struct v4l2_buffer for processing during > > VIDIOC_PREPARE_BUF > > 7. VIDIOC_PREPARE_BUF now uses struct v4l2_buffer as its argument > > > > > > Documentation/DocBook/media/v4l/io.xml | 17 +++ > > Documentation/DocBook/media/v4l/v4l2.xml | 2 + > > .../DocBook/media/v4l/vidioc-create-bufs.xml | 152 ++++++++++++++++++++ > > .../DocBook/media/v4l/vidioc-prepare-buf.xml | 96 ++++++++++++ > > drivers/media/video/v4l2-compat-ioctl32.c | 68 ++++++++- > > drivers/media/video/v4l2-ioctl.c | 32 ++++ > > include/linux/videodev2.h | 16 ++ > > include/media/v4l2-ioctl.h | 2 + > > 8 files changed, 377 insertions(+), 8 deletions(-) > > create mode 100644 Documentation/DocBook/media/v4l/vidioc-create-bufs.xml > > create mode 100644 Documentation/DocBook/media/v4l/vidioc-prepare-buf.xml > > > > diff --git a/Documentation/DocBook/media/v4l/io.xml b/Documentation/DocBook/media/v4l/io.xml > > index 227e7ac..6249d0e 100644 > > --- a/Documentation/DocBook/media/v4l/io.xml > > +++ b/Documentation/DocBook/media/v4l/io.xml > > @@ -927,6 +927,23 @@ ioctl is called.</entry> > > Applications set or clear this flag before calling the > > <constant>VIDIOC_QBUF</constant> ioctl.</entry> > > </row> > > + <row> > > + <entry><constant>V4L2_BUF_FLAG_NO_CACHE_INVALIDATE</constant></entry> > > + <entry>0x0400</entry> > > + <entry>Caches do not have to be invalidated for this buffer. > > +Typically applications shall use this flag, if the data, captured in the buffer > > +is not going to br touched by the CPU, instead the buffer will, probably, be > > +passed on to a DMA-capable hardware unit for further processing or output. > > +</entry> > > + </row> > > + <row> > > + <entry><constant>V4L2_BUF_FLAG_NO_CACHE_CLEAN</constant></entry> > > + <entry>0x0800</entry> > > + <entry>Caches do not have to be cleaned for this buffer. > > +Typically applications shall use this flag for output buffers, if the data > > +in this buffer has not been created by the CPU, but by some DMA-capable unit, > > +in which case caches have not been used.</entry> > > + </row> > > </tbody> > > </tgroup> > > </table> > > diff --git a/Documentation/DocBook/media/v4l/v4l2.xml b/Documentation/DocBook/media/v4l/v4l2.xml > > index 0d05e87..06bb179 100644 > > --- a/Documentation/DocBook/media/v4l/v4l2.xml > > +++ b/Documentation/DocBook/media/v4l/v4l2.xml > > @@ -462,6 +462,7 @@ and discussions on the V4L mailing list.</revremark> > > &sub-close; > > &sub-ioctl; > > <!-- All ioctls go here. --> > > + &sub-create-bufs; > > &sub-cropcap; > > &sub-dbg-g-chip-ident; > > &sub-dbg-g-register; > > @@ -504,6 +505,7 @@ and discussions on the V4L mailing list.</revremark> > > &sub-queryctrl; > > &sub-query-dv-preset; > > &sub-querystd; > > + &sub-prepare-buf; > > &sub-reqbufs; > > &sub-s-hw-freq-seek; > > &sub-streamon; > > diff --git a/Documentation/DocBook/media/v4l/vidioc-create-bufs.xml b/Documentation/DocBook/media/v4l/vidioc-create-bufs.xml > > new file mode 100644 > > index 0000000..5f0158c > > --- /dev/null > > +++ b/Documentation/DocBook/media/v4l/vidioc-create-bufs.xml > > @@ -0,0 +1,152 @@ > > +<refentry id="vidioc-create-bufs"> > > + <refmeta> > > + <refentrytitle>ioctl VIDIOC_CREATE_BUFS</refentrytitle> > > + &manvol; > > + </refmeta> > > + > > + <refnamediv> > > + <refname>VIDIOC_CREATE_BUFS</refname> > > + <refpurpose>Create buffers for Memory Mapped or User Pointer I/O</refpurpose> > > + </refnamediv> > > + > > + <refsynopsisdiv> > > + <funcsynopsis> > > + <funcprototype> > > + <funcdef>int <function>ioctl</function></funcdef> > > + <paramdef>int <parameter>fd</parameter></paramdef> > > + <paramdef>int <parameter>request</parameter></paramdef> > > + <paramdef>struct v4l2_create_buffers *<parameter>argp</parameter></paramdef> > > + </funcprototype> > > + </funcsynopsis> > > + </refsynopsisdiv> > > + > > + <refsect1> > > + <title>Arguments</title> > > + > > + <variablelist> > > + <varlistentry> > > + <term><parameter>fd</parameter></term> > > + <listitem> > > + <para>&fd;</para> > > + </listitem> > > + </varlistentry> > > + <varlistentry> > > + <term><parameter>request</parameter></term> > > + <listitem> > > + <para>VIDIOC_CREATE_BUFS</para> > > + </listitem> > > + </varlistentry> > > + <varlistentry> > > + <term><parameter>argp</parameter></term> > > + <listitem> > > + <para></para> > > + </listitem> > > + </varlistentry> > > + </variablelist> > > + </refsect1> > > + > > + <refsect1> > > + <title>Description</title> > > + > > + <para>This ioctl is used to create buffers for <link linkend="mmap">memory > > +mapped</link> or <link linkend="userp">user pointer</link> > > +I/O. It can be used as an alternative to the <constant>VIDIOC_REQBUFS</constant> > > +ioctl, when a tighter control over buffers is required. This ioctl can be called > > +multiple times to create buffers of different sizes. > > It looks like there is a </para> tag missing, that line should be: > > +multiple times to create buffers of different sizes. </para> > > Otherwise the compilation fails. Right, will be fixed. Thanks Guennadi --- Guennadi Liakhovetski, Ph.D. Freelance Open-Source Software Developer http://www.open-technology.de/ -- To unsubscribe from this list: send the line "unsubscribe linux-media" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
