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Diffstat (limited to 'Documentation/media/kapi/v4l2-device.rst')
| -rw-r--r-- | Documentation/media/kapi/v4l2-device.rst | 24 |
1 files changed, 12 insertions, 12 deletions
diff --git a/Documentation/media/kapi/v4l2-device.rst b/Documentation/media/kapi/v4l2-device.rst index c9115bcd8a9d..6c58bbbaa66f 100644 --- a/Documentation/media/kapi/v4l2-device.rst +++ b/Documentation/media/kapi/v4l2-device.rst @@ -7,7 +7,7 @@ would embed this struct inside a larger struct. You must register the device instance by calling: - :cpp:func:`v4l2_device_register <v4l2_device_register>` + :c:func:`v4l2_device_register <v4l2_device_register>` (dev, :c:type:`v4l2_dev <v4l2_device>`). Registration will initialize the :c:type:`v4l2_device` struct. If the @@ -23,12 +23,12 @@ properly initialized and registered :c:type:`media_device` instance. If :c:type:`v4l2_dev <v4l2_device>`\ ->name is empty then it will be set to a value derived from dev (driver name followed by the bus_id, to be precise). -If you set it up before calling :cpp:func:`v4l2_device_register` then it will +If you set it up before calling :c:func:`v4l2_device_register` then it will be untouched. If dev is ``NULL``, then you **must** setup :c:type:`v4l2_dev <v4l2_device>`\ ->name before calling -:cpp:func:`v4l2_device_register`. +:c:func:`v4l2_device_register`. -You can use :cpp:func:`v4l2_device_set_name` to set the name based on a driver +You can use :c:func:`v4l2_device_set_name` to set the name based on a driver name and a driver-global atomic_t instance. This will generate names like ``ivtv0``, ``ivtv1``, etc. If the name ends with a digit, then it will insert a dash: ``cx18-0``, ``cx18-1``, etc. This function returns the instance number. @@ -46,7 +46,7 @@ in ``include/media/subdevice.h``. V4L2 devices are unregistered by calling: - :cpp:func:`v4l2_device_unregister` + :c:func:`v4l2_device_unregister` (:c:type:`v4l2_dev <v4l2_device>`). If the dev->driver_data field points to :c:type:`v4l2_dev <v4l2_device>`, @@ -58,12 +58,12 @@ happens the parent device becomes invalid. Since :c:type:`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: - :cpp:func:`v4l2_device_disconnect` + :c:func:`v4l2_device_disconnect` (:c:type:`v4l2_dev <v4l2_device>`). This does *not* unregister the subdevs, so you still need to call the -:cpp:func:`v4l2_device_unregister` function for that. If your driver is not -hotpluggable, then there is no need to call :cpp:func:`v4l2_device_disconnect`. +:c:func:`v4l2_device_unregister` function for that. If your driver is not +hotpluggable, then there is no need to call :c:func:`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 @@ -117,7 +117,7 @@ The recommended approach is as follows: If you have multiple device nodes then it can be difficult to know when it is safe to unregister :c:type:`v4l2_device` for hotpluggable devices. For this purpose :c:type:`v4l2_device` has refcounting support. The refcount is -increased whenever :cpp:func:`video_register_device` is called and it is +increased whenever :c:func:`video_register_device` is called and it is decreased whenever that device node is released. When the refcount reaches zero, then the :c:type:`v4l2_device` release() callback is called. You can do your final cleanup there. @@ -125,16 +125,16 @@ do your final cleanup there. If other device nodes (e.g. ALSA) are created, then you can increase and decrease the refcount manually as well by calling: - :cpp:func:`v4l2_device_get` + :c:func:`v4l2_device_get` (:c:type:`v4l2_dev <v4l2_device>`). or: - :cpp:func:`v4l2_device_put` + :c:func:`v4l2_device_put` (:c:type:`v4l2_dev <v4l2_device>`). Since the initial refcount is 1 you also need to call -:cpp:func:`v4l2_device_put` in the ``disconnect()`` callback (for USB devices) +:c:func:`v4l2_device_put` in the ``disconnect()`` callback (for USB devices) or in the ``remove()`` callback (for e.g. PCI devices), otherwise the refcount will never reach 0. |