From 539a7555b31e65e66fb84c881d07d2bf18c974d0 Mon Sep 17 00:00:00 2001 From: "brandon@ifup.org" Date: Fri, 20 Jun 2008 22:58:53 -0300 Subject: V4L/DVB (8078): Introduce "index" attribute for persistent video4linux device nodes A number of V4L drivers have a mod param to specify their preferred minors. This is because it is often desirable for applications to have a static /dev name for a particular device. However, using minors has several disadvantages: 1) the requested minor may already be taken 2) using a mod param is driver specific 3) it requires every driver to add a param 4) requires configuration by hand This patch introduces an "index" attribute that when combined with udev rules can create static device paths like this: /dev/v4l/by-path/pci-0000\:00\:1d.2-usb-0\:1\:1.0-video0 /dev/v4l/by-path/pci-0000\:00\:1d.2-usb-0\:1\:1.0-video1 /dev/v4l/by-path/pci-0000\:00\:1d.2-usb-0\:1\:1.0-video2 $ ls -la /dev/v4l/by-path/pci-0000\:00\:1d.2-usb-0\:1\:1.0-video0 lrwxrwxrwx 1 root root 12 2008-04-28 00:02 /dev/v4l/by-path/pci-0000:00:1d.2-usb-0:1:1.0-video0 -> ../../video1 These paths are steady across reboots and should be resistant to rearranging across Kernel versions. video_register_device_index is available to drivers to request a specific index number. Signed-off-by: Brandon Philips Signed-off-by: Kees Cook Signed-off-by: Kay Sievers Signed-off-by: Mauro Carvalho Chehab --- include/media/v4l2-dev.h | 4 ++++ 1 file changed, 4 insertions(+) (limited to 'include/media') diff --git a/include/media/v4l2-dev.h b/include/media/v4l2-dev.h index 40b0810a595..9e6e4f18e94 100644 --- a/include/media/v4l2-dev.h +++ b/include/media/v4l2-dev.h @@ -96,6 +96,8 @@ struct video_device int type; /* v4l1 */ int type2; /* v4l2 */ int minor; + /* attribute to diferentiate multiple indexs on one physical device */ + int index; int debug; /* Activates debug level*/ @@ -347,6 +349,8 @@ void *priv; /* Version 2 functions */ extern int video_register_device(struct video_device *vfd, int type, int nr); +int video_register_device_index(struct video_device *vfd, int type, int nr, + int index); void video_unregister_device(struct video_device *); extern int video_ioctl2(struct inode *inode, struct file *file, unsigned int cmd, unsigned long arg); -- cgit v1.2.3