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authorLaurent Pinchart <laurent.pinchart@ideasonboard.com>2009-12-09 14:38:49 +0300
committerMauro Carvalho Chehab <mchehab@redhat.com>2011-03-22 02:32:42 +0300
commit2096a5dcf9704f5a86ecba37169eb813aaf0431c (patch)
tree21e7d870302a7c6748667a785b465a7a84805228 /Documentation/video4linux
parent0070d91e5b5ae594116202ab7d62d8264830b1cd (diff)
downloadlinux-2096a5dcf9704f5a86ecba37169eb813aaf0431c.tar.xz
[media] v4l: subdev: Add device node support
Create a device node named subdevX for every registered subdev. As the device node is registered before the subdev core::s_config function is called, return -EGAIN on open until initialization completes. Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com> Signed-off-by: Vimarsh Zutshi <vimarsh.zutshi@gmail.com> Acked-by: Hans Verkuil <hverkuil@xs4all.nl> Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>
Diffstat (limited to 'Documentation/video4linux')
-rw-r--r--Documentation/video4linux/v4l2-framework.txt16
1 files changed, 16 insertions, 0 deletions
diff --git a/Documentation/video4linux/v4l2-framework.txt b/Documentation/video4linux/v4l2-framework.txt
index f22f35c271f3..8b358710b2f7 100644
--- a/Documentation/video4linux/v4l2-framework.txt
+++ b/Documentation/video4linux/v4l2-framework.txt
@@ -319,6 +319,22 @@ controlled through GPIO pins. This distinction is only relevant when setting
up the device, but once the subdev is registered it is completely transparent.
+V4L2 sub-device userspace API
+-----------------------------
+
+Beside exposing a kernel API through the v4l2_subdev_ops structure, V4L2
+sub-devices can also be controlled directly by userspace applications.
+
+Device nodes named v4l-subdevX can be created in /dev to access sub-devices
+directly. If a sub-device supports direct userspace configuration it must set
+the V4L2_SUBDEV_FL_HAS_DEVNODE flag before being registered.
+
+After registering sub-devices, the v4l2_device driver can create device nodes
+for all registered sub-devices marked with V4L2_SUBDEV_FL_HAS_DEVNODE by calling
+v4l2_device_register_subdev_nodes(). Those device nodes will be automatically
+removed when sub-devices are unregistered.
+
+
I2C sub-device drivers
----------------------