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. -- Regards, Sylwester Nawrocki -- Sylwester Nawrocki Samsung Poland R&D Center -- 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
