[media] v4l2-framework: update documentation
'parent' was renamed to 'dev_parent'. Clarify how/when this should be used. Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com> Acked-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com> Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>
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@ -574,9 +574,13 @@ of the video device exits.
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The default video_device_release() callback just calls kfree to free the
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allocated memory.
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There is also a video_device_release_empty() function that does nothing
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(is empty) and can be used if the struct is embedded and there is nothing
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to do when it is released.
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You should also set these fields:
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- v4l2_dev: set to the v4l2_device parent device.
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- v4l2_dev: must be set to the v4l2_device parent device.
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- name: set to something descriptive and unique.
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@ -613,15 +617,16 @@ You should also set these fields:
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If you want to have a separate priority state per (group of) device node(s),
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then you can point it to your own struct v4l2_prio_state.
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- parent: you only set this if v4l2_device was registered with NULL as
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- dev_parent: you only set this if v4l2_device was registered with NULL as
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the parent device struct. This only happens in cases where one hardware
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device has multiple PCI devices that all share the same v4l2_device core.
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The cx88 driver is an example of this: one core v4l2_device struct, but
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it is used by both an raw video PCI device (cx8800) and a MPEG PCI device
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(cx8802). Since the v4l2_device cannot be associated with a particular
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PCI device it is setup without a parent device. But when the struct
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video_device is setup you do know which parent PCI device to use.
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it is used by both a raw video PCI device (cx8800) and a MPEG PCI device
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(cx8802). Since the v4l2_device cannot be associated with two PCI devices
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at the same time it is setup without a parent device. But when the struct
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video_device is initialized you *do* know which parent PCI device to use and
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so you set dev_device to the correct PCI device.
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- flags: optional. Set to V4L2_FL_USE_FH_PRIO if you want to let the framework
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handle the VIDIOC_G/S_PRIORITY ioctls. This requires that you use struct
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