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authorHans Verkuil <hverkuil@xs4all.nl>2009-03-14 08:28:45 -0300
committerMauro Carvalho Chehab <mchehab@redhat.com>2009-03-30 12:43:22 -0300
commitae6cfaace120f4330715b56265ce0e4a710e1276 (patch)
treeed01c11218132e92ce8fe4872fe26c572c3c8842 /Documentation/video4linux/v4l2-framework.txt
parent6273fda6e32e2cd9a478545d0cbc15ac497b1f4b (diff)
V4L/DVB (11044): v4l2-device: add v4l2_device_disconnect
Call v4l2_device_disconnect when the parent of a hotpluggable device disconnects. This ensures that you do not have a pointer to a device that is no longer present. Signed-off-by: Hans Verkuil <hverkuil@xs4all.nl> Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>
Diffstat (limited to 'Documentation/video4linux/v4l2-framework.txt')
-rw-r--r--Documentation/video4linux/v4l2-framework.txt11
1 files changed, 11 insertions, 0 deletions
diff --git a/Documentation/video4linux/v4l2-framework.txt b/Documentation/video4linux/v4l2-framework.txt
index 4207590b2ac8..a31177390e55 100644
--- a/Documentation/video4linux/v4l2-framework.txt
+++ b/Documentation/video4linux/v4l2-framework.txt
@@ -105,6 +105,17 @@ You unregister with:
Unregistering will also automatically unregister all subdevs from the device.
+If you have a hotpluggable device (e.g. a USB device), then when a disconnect
+happens the parent device becomes invalid. Since v4l2_device has a pointer to
+that parent device it has to be cleared as well to mark that the parent is
+gone. To do this call:
+
+ v4l2_device_disconnect(struct v4l2_device *v4l2_dev);
+
+This does *not* unregister the subdevs, so you still need to call the
+v4l2_device_unregister() function for that. If your driver is not hotpluggable,
+then there is no need to call v4l2_device_disconnect().
+
Sometimes you need to iterate over all devices registered by a specific
driver. This is usually the case if multiple device drivers use the same
hardware. E.g. the ivtvfb driver is a framebuffer driver that uses the ivtv