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authorMauro Carvalho Chehab <mchehab@s-opensource.com>2016-07-17 20:50:45 -0300
committerMauro Carvalho Chehab <mchehab@s-opensource.com>2016-07-17 22:51:26 -0300
commita965d2024fe6f45a33462a62826c23a2175f3d5a (patch)
tree50e6aad7842652be8f9efbd66bf852bd1a867abe /Documentation/media/v4l-drivers/uvcvideo.rst
parentc0d0138255b37f362bb8559342cc0ac7da59b1be (diff)
downloadlinux-0-day-a965d2024fe6f45a33462a62826c23a2175f3d5a.tar.gz
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[media] doc-rst: add documentation for uvcvideo
Convert it to ReST and add to media/v4l-drivers book. Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>
Diffstat (limited to 'Documentation/media/v4l-drivers/uvcvideo.rst')
-rw-r--r--Documentation/media/v4l-drivers/uvcvideo.rst48
1 files changed, 32 insertions, 16 deletions
diff --git a/Documentation/media/v4l-drivers/uvcvideo.rst b/Documentation/media/v4l-drivers/uvcvideo.rst
index 35ce19cddcf80..d68b3d59a4b50 100644
--- a/Documentation/media/v4l-drivers/uvcvideo.rst
+++ b/Documentation/media/v4l-drivers/uvcvideo.rst
@@ -1,5 +1,5 @@
-Linux USB Video Class (UVC) driver
-==================================
+The Linux USB Video Class (UVC) driver
+======================================
This file documents some driver-specific aspects of the UVC driver, such as
driver-specific ioctls and implementation notes.
@@ -11,7 +11,8 @@ linux-uvc-devel@lists.berlios.de.
Extension Unit (XU) support
---------------------------
-1. Introduction
+Introduction
+~~~~~~~~~~~~
The UVC specification allows for vendor-specific extensions through extension
units (XUs). The Linux UVC driver supports extension unit controls (XU controls)
@@ -31,7 +32,8 @@ maximum flexibility.
Both mechanisms complement each other and are described in more detail below.
-2. Control mappings
+Control mappings
+~~~~~~~~~~~~~~~~
The UVC driver provides an API for user space applications to define so-called
control mappings at runtime. These allow for individual XU controls or byte
@@ -82,7 +84,8 @@ For details on the UVCIOC_CTRL_QUERY ioctl please refer to the section titled
"IOCTL reference" below.
-4. Security
+Security
+~~~~~~~~
The API doesn't currently provide a fine-grained access control facility. The
UVCIOC_CTRL_ADD and UVCIOC_CTRL_MAP ioctls require super user permissions.
@@ -90,20 +93,24 @@ UVCIOC_CTRL_ADD and UVCIOC_CTRL_MAP ioctls require super user permissions.
Suggestions on how to improve this are welcome.
-5. Debugging
+Debugging
+~~~~~~~~~
In order to debug problems related to XU controls or controls in general it is
recommended to enable the UVC_TRACE_CONTROL bit in the module parameter 'trace'.
This causes extra output to be written into the system log.
-6. IOCTL reference
+IOCTL reference
+~~~~~~~~~~~~~~~
----- UVCIOC_CTRL_MAP - Map a UVC control to a V4L2 control ----
+UVCIOC_CTRL_MAP - Map a UVC control to a V4L2 control
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
Argument: struct uvc_xu_control_mapping
-Description:
+**Description**:
+
This ioctl creates a mapping between a UVC control or part of a UVC
control and a V4L2 control. Once mappings are defined, userspace
applications can access vendor-defined UVC control through the V4L2
@@ -122,7 +129,8 @@ Description:
For signed integer V4L2 controls the data_type field should be set to
UVC_CTRL_DATA_TYPE_SIGNED. Other values are currently ignored.
-Return value:
+**Return value**:
+
On success 0 is returned. On error -1 is returned and errno is set
appropriately.
@@ -137,7 +145,10 @@ Return value:
EEXIST
Mapping already exists.
-Data types:
+**Data types**:
+
+.. code-block:: none
+
* struct uvc_xu_control_mapping
__u32 id V4L2 control identifier
@@ -170,11 +181,12 @@ Data types:
UVC_CTRL_DATA_TYPE_BITMASK Bitmask
----- UVCIOC_CTRL_QUERY - Query a UVC XU control ----
-
+UVCIOC_CTRL_QUERY - Query a UVC XU control
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
Argument: struct uvc_xu_control_query
-Description:
+**Description**:
+
This ioctl queries a UVC XU control identified by its extension unit ID
and control selector.
@@ -213,7 +225,8 @@ Description:
important for the result of the UVC_GET_LEN requests, which is always
returned as a little-endian 16-bit integer by the device.
-Return value:
+**Return value**:
+
On success 0 is returned. On error -1 is returned and errno is set
appropriately.
@@ -229,7 +242,10 @@ Return value:
EFAULT
The data pointer references an inaccessible memory area.
-Data types:
+**Data types**:
+
+.. code-block:: none
+
* struct uvc_xu_control_query
__u8 unit Extension unit ID