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>
---
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/v4l2.xml | 2 +
.../DocBook/media/v4l/vidioc-create-bufs.xml | 153 ++++++++++++++++++++
.../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 +
7 files changed, 361 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/v4l2.xml b/Documentation/DocBook/media/v4l/v4l2.xml
index a7fd76d..10fe7c7 100644
--- a/Documentation/DocBook/media/v4l/v4l2.xml
+++ b/Documentation/DocBook/media/v4l/v4l2.xml
@@ -453,6 +453,7 @@ 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;
@@ -495,6 +496,7 @@ 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..3003530
--- /dev/null
+++ b/Documentation/DocBook/media/v4l/vidioc-create-bufs.xml
@@ -0,0 +1,153 @@
+<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.
+
+ <para>To allocate device buffers applications initialize all
+fields of the <structname>v4l2_create_buffers</structname> structure.
+They set the <structfield>type</structfield> field in the
+<structname>v4l2_format</structname> structure, embedded in this
+structure, to the respective stream or buffer type.
+<structfield>count</structfield> must be set to the number of required
+buffers. <structfield>memory</structfield> specifies the required I/O
+method. Applications have two possibilities to specify the size of buffers
+to be prepared: they can either set the <structfield>size</structfield>
+field explicitly, or fill in the frame format data in the
+<structfield>format</structfield> field. In the latter case buffer sizes
+will be calculated automatically by the driver. The
+<structfield>reserved</structfield> array must be zeroed. When the ioctl
+is called with a pointer to this structure the driver will attempt to allocate
+the requested number of buffers and it stores the actual number
+allocated and the starting index in the <structfield>count</structfield> and
+the <structfield>index</structfield> fields respectively.
+<structfield>count</structfield> can be smaller than the number requested,
+even zero, when the driver runs out of free memory. A larger number is also
+possible when the driver requires more buffers to function correctly.</para>
+ <para>When the I/O method is not supported the ioctl
+returns an &EINVAL;.</para>
+
+ <table pgwide="1" frame="none" id="v4l2-create-buffers">
+ <title>struct <structname>v4l2_create_buffers</structname></title>
+ <tgroup cols="3">
+ &cs-str;
+ <tbody valign="top">
+ <row>
+ <entry>__u32</entry>
+ <entry><structfield>index</structfield></entry>
+ <entry>The starting buffer index, returned by the driver.</entry>
+ </row>
+ <row>
+ <entry>__u32</entry>
+ <entry><structfield>count</structfield></entry>
+ <entry>The number of buffers requested or granted.</entry>
+ </row>
+ <row>
+ <entry>&v4l2-memory;</entry>
+ <entry><structfield>memory</structfield></entry>
+ <entry>Applications set this field to
+<constant>V4L2_MEMORY_MMAP</constant> or
+<constant>V4L2_MEMORY_USERPTR</constant>.</entry>
+ </row>
+ <row>
+ <entry>__u32</entry>
+ <entry><structfield>size</structfield></entry>
+ <entry>Explicit size of buffers, being created.</entry>
+ </row>
+ <row>
+ <entry>&v4l2-format;</entry>
+ <entry><structfield>format</structfield></entry>
+ <entry>Application has to set the <structfield>type</structfield>
+field, other fields should be used, if the application wants to allocate buffers
+for a specific frame format.</entry>
+ </row>
+ <row>
+ <entry>__u32</entry>
+ <entry><structfield>reserved</structfield>[2]</entry>
+ <entry>A place holder for future extensions.</entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
+ </refsect1>
+
+ <refsect1>
+ &return-value;
+
+ <variablelist>
+ <varlistentry>
+ <term><errorcode>ENOMEM</errorcode></term>
+ <listitem>
+ <para>No memory to allocate buffers for <link linkend="mmap">memory
+mapped</link> I/O.</para>
+ </listitem>
+ </varlistentry>
+ <varlistentry>
+ <term><errorcode>EINVAL</errorcode></term>
+ <listitem>
+ <para>The buffer type (<structfield>type</structfield> field) or the
+requested I/O method (<structfield>memory</structfield>) is not
+supported.</para>
+ </listitem>
+ </varlistentry>
+ </variablelist>
+ </refsect1>
+</refentry>
+
+<!--
+Local Variables:
+mode: sgml
+sgml-parent-document: "v4l2.sgml"
+indent-tabs-mode: nil
+End:
+-->
diff --git a/Documentation/DocBook/media/v4l/vidioc-prepare-buf.xml b/Documentation/DocBook/media/v4l/vidioc-prepare-buf.xml
new file mode 100644
index 0000000..9532d28
--- /dev/null
+++ b/Documentation/DocBook/media/v4l/vidioc-prepare-buf.xml
@@ -0,0 +1,96 @@
+<refentry id="vidioc-prepare-buf">
+ <refmeta>
+ <refentrytitle>ioctl VIDIOC_PREPARE_BUF</refentrytitle>
+ &manvol;
+ </refmeta>
+
+ <refnamediv>
+ <refname>VIDIOC_PREPARE_BUF</refname>
+ <refpurpose>Prepare a buffer for 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_buffer *<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_PREPARE_BUF</para>
+ </listitem>
+ </varlistentry>
+ <varlistentry>
+ <term><parameter>argp</parameter></term>
+ <listitem>
+ <para></para>
+ </listitem>
+ </varlistentry>
+ </variablelist>
+ </refsect1>
+
+ <refsect1>
+ <title>Description</title>
+
+ <para>Applications can optionally call the
+<constant>VIDIOC_PREPARE_BUF</constant> ioctl
+to pass ownership of the buffer to the driver before actually enqueuing it, and
+to prepare it for future I/O.
+Such preparations may include cache invalidation or cleaning. Performing them
+in advance saves time during the actual I/O. In case such cache operations are
+not required, the application can use one of
+<constant>V4L2_BUF_FLAG_NO_CACHE_INVALIDATE</constant> and
+<constant>V4L2_BUF_FLAG_NO_CACHE_CLEAN</constant> flags to skip the respective
+step.</para>
+
+ <para>The <structname>v4l2_buffer</structname> structure is
+specified in <xref linkend="buffer" />.</para>
+ </refsect1>
+
+ <refsect1>
+ &return-value;
+
+ <variablelist>
+ <varlistentry>
+ <term><errorcode>EBUSY</errorcode></term>
+ <listitem>
+ <para>File I/O is in progress.</para>
+ </listitem>
+ </varlistentry>
+ <varlistentry>
+ <term><errorcode>EINVAL</errorcode></term>
+ <listitem>
+ <para>The buffer <structfield>type</structfield> is not
+supported, or the <structfield>index</structfield> is out of bounds,
+or no buffers have been allocated yet, or the
+<structfield>userptr</structfield> or
+<structfield>length</structfield> are invalid.</para>
+ </listitem>
+ </varlistentry>
+ </variablelist>
+ </refsect1>
+</refentry>
+
+<!--
+Local Variables:
+mode: sgml
+sgml-parent-document: "v4l2.sgml"
+indent-tabs-mode: nil
+End:
+-->
diff --git a/drivers/media/video/v4l2-compat-ioctl32.c b/drivers/media/video/v4l2-compat-ioctl32.c
index 7c26947..6fcc7e0 100644
--- a/drivers/media/video/v4l2-compat-ioctl32.c
+++ b/drivers/media/video/v4l2-compat-ioctl32.c
@@ -159,11 +159,16 @@ struct v4l2_format32 {
} fmt;
};
-static int get_v4l2_format32(struct v4l2_format *kp, struct v4l2_format32 __user *up)
+struct v4l2_create_buffers32 {
+ __u32 index; /* output: buffers index...index + count - 1 have been created */
+ __u32 count;
+ enum v4l2_memory memory;
+ __u32 size; /* Explicit size, e.g., for compressed streams */
+ struct v4l2_format32 format; /* "type" is used always, the rest if size == 0 */
+};
+
+static int __get_v4l2_format32(struct v4l2_format *kp, struct v4l2_format32 __user *up)
{
- if (!access_ok(VERIFY_READ, up, sizeof(struct v4l2_format32)) ||
- get_user(kp->type, &up->type))
- return -EFAULT;
switch (kp->type) {
case V4L2_BUF_TYPE_VIDEO_CAPTURE:
case V4L2_BUF_TYPE_VIDEO_OUTPUT:
@@ -192,11 +197,24 @@ static int get_v4l2_format32(struct v4l2_format *kp, struct v4l2_format32 __user
}
}
-static int put_v4l2_format32(struct v4l2_format *kp, struct v4l2_format32 __user *up)
+static int get_v4l2_format32(struct v4l2_format *kp, struct v4l2_format32 __user *up)
+{
+ if (!access_ok(VERIFY_READ, up, sizeof(struct v4l2_format32)) ||
+ get_user(kp->type, &up->type))
+ return -EFAULT;
+ return __get_v4l2_format32(kp, up);
+}
+
+static int get_v4l2_create32(struct v4l2_create_buffers *kp, struct v4l2_create_buffers32 __user *up)
+{
+ if (!access_ok(VERIFY_READ, up, sizeof(struct v4l2_create_buffers32)) ||
+ copy_from_user(kp, up, offsetof(struct v4l2_create_buffers32, format.fmt)))
+ return -EFAULT;
+ return __get_v4l2_format32(&kp->format, &up->format);
+}
+
+static int __put_v4l2_format32(struct v4l2_format *kp, struct v4l2_format32 __user *up)
{
- if (!access_ok(VERIFY_WRITE, up, sizeof(struct v4l2_format32)) ||
- put_user(kp->type, &up->type))
- return -EFAULT;
switch (kp->type) {
case V4L2_BUF_TYPE_VIDEO_CAPTURE:
case V4L2_BUF_TYPE_VIDEO_OUTPUT:
@@ -225,6 +243,22 @@ static int put_v4l2_format32(struct v4l2_format *kp, struct v4l2_format32 __user
}
}
+static int put_v4l2_format32(struct v4l2_format *kp, struct v4l2_format32 __user *up)
+{
+ if (!access_ok(VERIFY_WRITE, up, sizeof(struct v4l2_format32)) ||
+ put_user(kp->type, &up->type))
+ return -EFAULT;
+ return __put_v4l2_format32(kp, up);
+}
+
+static int put_v4l2_create32(struct v4l2_create_buffers *kp, struct v4l2_create_buffers32 __user *up)
+{
+ if (!access_ok(VERIFY_WRITE, up, sizeof(struct v4l2_create_buffers32)) ||
+ copy_to_user(up, kp, offsetof(struct v4l2_create_buffers32, format.fmt)))
+ return -EFAULT;
+ return __put_v4l2_format32(&kp->format, &up->format);
+}
+
struct v4l2_standard32 {
__u32 index;
__u32 id[2]; /* __u64 would get the alignment wrong */
@@ -675,6 +709,8 @@ static int put_v4l2_ext_controls32(struct v4l2_ext_controls *kp, struct v4l2_ext
#define VIDIOC_G_EXT_CTRLS32 _IOWR('V', 71, struct v4l2_ext_controls32)
#define VIDIOC_S_EXT_CTRLS32 _IOWR('V', 72, struct v4l2_ext_controls32)
#define VIDIOC_TRY_EXT_CTRLS32 _IOWR('V', 73, struct v4l2_ext_controls32)
+#define VIDIOC_CREATE_BUFS32 _IOWR('V', 92, struct v4l2_create_buffers32)
+#define VIDIOC_PREPARE_BUF32 _IOWR('V', 93, struct v4l2_buffer32)
#define VIDIOC_OVERLAY32 _IOW ('V', 14, s32)
#define VIDIOC_STREAMON32 _IOW ('V', 18, s32)
@@ -693,6 +729,7 @@ static long do_video_ioctl(struct file *file, unsigned int cmd, unsigned long ar
struct v4l2_input v2i;
struct v4l2_standard v2s;
struct v4l2_ext_controls v2ecs;
+ struct v4l2_create_buffers v2crt;
unsigned long vx;
int vi;
} karg;
@@ -722,6 +759,8 @@ static long do_video_ioctl(struct file *file, unsigned int cmd, unsigned long ar
case VIDIOC_S_INPUT32: cmd = VIDIOC_S_INPUT; break;
case VIDIOC_G_OUTPUT32: cmd = VIDIOC_G_OUTPUT; break;
case VIDIOC_S_OUTPUT32: cmd = VIDIOC_S_OUTPUT; break;
+ case VIDIOC_CREATE_BUFS32: cmd = VIDIOC_CREATE_BUFS; break;
+ case VIDIOC_PREPARE_BUF32: cmd = VIDIOC_PREPARE_BUF; break;
}
switch (cmd) {
@@ -746,6 +785,12 @@ static long do_video_ioctl(struct file *file, unsigned int cmd, unsigned long ar
compatible_arg = 0;
break;
+ case VIDIOC_CREATE_BUFS:
+ err = get_v4l2_create32(&karg.v2crt, up);
+ compatible_arg = 0;
+ break;
+
+ case VIDIOC_PREPARE_BUF:
case VIDIOC_QUERYBUF:
case VIDIOC_QBUF:
case VIDIOC_DQBUF:
@@ -818,6 +863,11 @@ static long do_video_ioctl(struct file *file, unsigned int cmd, unsigned long ar
err = put_v4l2_framebuffer32(&karg.v2fb, up);
break;
+ case VIDIOC_CREATE_BUFS:
+ err = put_v4l2_create32(&karg.v2crt, up);
+ break;
+
+ case VIDIOC_PREPARE_BUF:
case VIDIOC_G_FMT:
case VIDIOC_S_FMT:
case VIDIOC_TRY_FMT:
@@ -922,6 +972,8 @@ long v4l2_compat_ioctl32(struct file *file, unsigned int cmd, unsigned long arg)
case VIDIOC_DQEVENT:
case VIDIOC_SUBSCRIBE_EVENT:
case VIDIOC_UNSUBSCRIBE_EVENT:
+ case VIDIOC_CREATE_BUFS32:
+ case VIDIOC_PREPARE_BUF32:
ret = do_video_ioctl(file, cmd, arg);
break;
diff --git a/drivers/media/video/v4l2-ioctl.c b/drivers/media/video/v4l2-ioctl.c
index 213ba7d..40b8d96 100644
--- a/drivers/media/video/v4l2-ioctl.c
+++ b/drivers/media/video/v4l2-ioctl.c
@@ -259,6 +259,8 @@ static const char *v4l2_ioctls[] = {
[_IOC_NR(VIDIOC_DQEVENT)] = "VIDIOC_DQEVENT",
[_IOC_NR(VIDIOC_SUBSCRIBE_EVENT)] = "VIDIOC_SUBSCRIBE_EVENT",
[_IOC_NR(VIDIOC_UNSUBSCRIBE_EVENT)] = "VIDIOC_UNSUBSCRIBE_EVENT",
+ [_IOC_NR(VIDIOC_CREATE_BUFS)] = "VIDIOC_CREATE_BUFS",
+ [_IOC_NR(VIDIOC_PREPARE_BUF)] = "VIDIOC_PREPARE_BUF",
};
#define V4L2_IOCTLS ARRAY_SIZE(v4l2_ioctls)
@@ -2184,6 +2186,36 @@ static long __video_do_ioctl(struct file *file,
dbgarg(cmd, "type=0x%8.8x", sub->type);
break;
}
+ case VIDIOC_CREATE_BUFS:
+ {
+ struct v4l2_create_buffers *create = arg;
+
+ if (!ops->vidioc_create_bufs)
+ break;
+ ret = check_fmt(ops, create->format.type);
+ if (ret)
+ break;
+
+ if (create->size)
+ CLEAR_AFTER_FIELD(create, count);
+
+ ret = ops->vidioc_create_bufs(file, fh, create);
+
+ dbgarg(cmd, "count=%d\n", create->count);
+ break;
+ }
+ case VIDIOC_PREPARE_BUF:
+ {
+ struct v4l2_buffer *b = arg;
+
+ if (!ops->vidioc_prepare_buf)
+ break;
+
+ ret = ops->vidioc_prepare_buf(file, fh, b);
+
+ dbgarg(cmd, "index=%d", b->index);
+ break;
+ }
default:
{
bool valid_prio = true;
diff --git a/include/linux/videodev2.h b/include/linux/videodev2.h
index 8a4c309..8807462 100644
--- a/include/linux/videodev2.h
+++ b/include/linux/videodev2.h
@@ -643,6 +643,9 @@ struct v4l2_buffer {
#define V4L2_BUF_FLAG_ERROR 0x0040
#define V4L2_BUF_FLAG_TIMECODE 0x0100 /* timecode field is valid */
#define V4L2_BUF_FLAG_INPUT 0x0200 /* input field is valid */
+/* Cache handling flags */
+#define V4L2_BUF_FLAG_NO_CACHE_INVALIDATE 0x0400
+#define V4L2_BUF_FLAG_NO_CACHE_CLEAN 0x0800
/*
* O V E R L A Y P R E V I E W
@@ -1852,6 +1855,16 @@ struct v4l2_dbg_chip_ident {
__u32 revision; /* chip revision, chip specific */
} __attribute__ ((packed));
+/* VIDIOC_CREATE_BUFS */
+struct v4l2_create_buffers {
+ __u32 index; /* output: buffers index...index + count - 1 have been created */
+ __u32 count;
+ enum v4l2_memory memory;
+ __u32 size; /* Explicit size, e.g., for compressed streams */
+ struct v4l2_format format; /* "type" is used always, the rest if size == 0 */
+ __u32 reserved[4];
+};
+
/*
* I O C T L C O D E S F O R V I D E O D E V I C E S
*
@@ -1942,6 +1955,9 @@ struct v4l2_dbg_chip_ident {
#define VIDIOC_SUBSCRIBE_EVENT _IOW('V', 90, struct v4l2_event_subscription)
#define VIDIOC_UNSUBSCRIBE_EVENT _IOW('V', 91, struct v4l2_event_subscription)
+#define VIDIOC_CREATE_BUFS _IOWR('V', 92, struct v4l2_create_buffers)
+#define VIDIOC_PREPARE_BUF _IOW('V', 93, struct v4l2_buffer)
+
/* Reminder: when adding new ioctls please add support for them to
drivers/media/video/v4l2-compat-ioctl32.c as well! */
diff --git a/include/media/v4l2-ioctl.h b/include/media/v4l2-ioctl.h
index dd9f1e7..4d1c74a 100644
--- a/include/media/v4l2-ioctl.h
+++ b/include/media/v4l2-ioctl.h
@@ -122,6 +122,8 @@ struct v4l2_ioctl_ops {
int (*vidioc_qbuf) (struct file *file, void *fh, struct v4l2_buffer *b);
int (*vidioc_dqbuf) (struct file *file, void *fh, struct v4l2_buffer *b);
+ int (*vidioc_create_bufs)(struct file *file, void *fh, struct v4l2_create_buffers *b);
+ int (*vidioc_prepare_buf)(struct file *file, void *fh, struct v4l2_buffer *b);
int (*vidioc_overlay) (struct file *file, void *fh, unsigned int i);
int (*vidioc_g_fbuf) (struct file *file, void *fh,
--
1.7.2.5
--
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