diff options
Diffstat (limited to 'Documentation')
-rw-r--r-- | Documentation/video4linux/v4l2-framework.txt | 17 |
1 files changed, 5 insertions, 12 deletions
diff --git a/Documentation/video4linux/v4l2-framework.txt b/Documentation/video4linux/v4l2-framework.txt index e395a9cdc533..cb6c7eb51472 100644 --- a/Documentation/video4linux/v4l2-framework.txt +++ b/Documentation/video4linux/v4l2-framework.txt | |||
@@ -500,17 +500,11 @@ first free number. | |||
500 | Whenever a device node is created some attributes are also created for you. | 500 | Whenever a device node is created some attributes are also created for you. |
501 | If you look in /sys/class/video4linux you see the devices. Go into e.g. | 501 | If you look in /sys/class/video4linux you see the devices. Go into e.g. |
502 | video0 and you will see 'name' and 'index' attributes. The 'name' attribute | 502 | video0 and you will see 'name' and 'index' attributes. The 'name' attribute |
503 | is the 'name' field of the video_device struct. The 'index' attribute is | 503 | is the 'name' field of the video_device struct. |
504 | a device node index that can be assigned by the driver, or that is calculated | ||
505 | for you. | ||
506 | |||
507 | If you call video_register_device(), then the index is just increased by | ||
508 | 1 for each device node you register. The first video device node you register | ||
509 | always starts off with 0. | ||
510 | 504 | ||
511 | Alternatively you can call video_register_device_index() which is identical | 505 | The 'index' attribute is the index of the device node: for each call to |
512 | to video_register_device(), but with an extra index argument. Here you can | 506 | video_register_device() the index is just increased by 1. The first video |
513 | pass a specific index value (between 0 and 31) that should be used. | 507 | device node you register always starts with index 0. |
514 | 508 | ||
515 | Users can setup udev rules that utilize the index attribute to make fancy | 509 | Users can setup udev rules that utilize the index attribute to make fancy |
516 | device names (e.g. 'mpegX' for MPEG video capture device nodes). | 510 | device names (e.g. 'mpegX' for MPEG video capture device nodes). |
@@ -520,8 +514,7 @@ After the device was successfully registered, then you can use these fields: | |||
520 | - vfl_type: the device type passed to video_register_device. | 514 | - vfl_type: the device type passed to video_register_device. |
521 | - minor: the assigned device minor number. | 515 | - minor: the assigned device minor number. |
522 | - num: the device kernel number (i.e. the X in videoX). | 516 | - num: the device kernel number (i.e. the X in videoX). |
523 | - index: the device index number (calculated or set explicitly using | 517 | - index: the device index number. |
524 | video_register_device_index). | ||
525 | 518 | ||
526 | If the registration failed, then you need to call video_device_release() | 519 | If the registration failed, then you need to call video_device_release() |
527 | to free the allocated video_device struct, or free your own struct if the | 520 | to free the allocated video_device struct, or free your own struct if the |