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Merge branch 'v4l_for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/mchehab/linux-media
Pull media updates from Mauro Carvalho Chehab: "This is the first part of the media patches for v3.6. This patch series contain: - new DVB frontend: rtl2832 - new video drivers: adv7393 - some unused files got removed - a selection API cleanup between V4L2 and V4L2 subdev API's - a major redesign at v4l-ioctl2, in order to clean it up - several driver fixes and improvements." * 'v4l_for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/mchehab/linux-media: (174 commits) v4l: Export v4l2-common.h in include/linux/Kbuild media: Revert "[media] Terratec Cinergy S2 USB HD Rev.2" [media] media: Use pr_info not homegrown pr_reg macro [media] Terratec Cinergy S2 USB HD Rev.2 [media] v4l: Correct conflicting V4L2 subdev selection API documentation [media] Feature removal: V4L2 selections API target and flag definitions [media] v4l: Unify selection flags documentation [media] v4l: Unify selection flags [media] v4l: Common documentation for selection targets [media] v4l: Unify selection targets across V4L2 and V4L2 subdev interfaces [media] v4l: Remove "_ACTUAL" from subdev selection API target definition names [media] V4L: Remove "_ACTIVE" from the selection target name definitions [media] media: dvb-usb: print mac address via native %pM [media] s5p-tv: Use module_i2c_driver in sii9234_drv.c file [media] media: gpio-ir-recv: add allowed_protos for platform data [media] s5p-jpeg: Use module_platform_driver in jpeg-core.c file [media] saa7134: fix spelling of detach in label [media] cx88-blackbird: replace ioctl by unlocked_ioctl [media] cx88: don't use current_norm [media] cx88: fix a number of v4l2-compliance violations ...
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Linus Torvalds
@@ -594,6 +594,15 @@ You should also set these fields:
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unlocked_ioctl file operation is called this lock will be taken by the
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core and released afterwards. See the next section for more details.
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- queue: a pointer to the struct vb2_queue associated with this device node.
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If queue is non-NULL, and queue->lock is non-NULL, then queue->lock is
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used for the queuing ioctls (VIDIOC_REQBUFS, CREATE_BUFS, QBUF, DQBUF,
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QUERYBUF, PREPARE_BUF, STREAMON and STREAMOFF) instead of the lock above.
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That way the vb2 queuing framework does not have to wait for other ioctls.
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This queue pointer is also used by the vb2 helper functions to check for
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queuing ownership (i.e. is the filehandle calling it allowed to do the
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operation).
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- prio: keeps track of the priorities. Used to implement VIDIOC_G/S_PRIORITY.
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If left to NULL, then it will use the struct v4l2_prio_state in v4l2_device.
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If you want to have a separate priority state per (group of) device node(s),
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@@ -647,47 +656,43 @@ manually set the struct media_entity type and name fields.
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A reference to the entity will be automatically acquired/released when the
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video device is opened/closed.
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v4l2_file_operations and locking
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--------------------------------
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ioctls and locking
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------------------
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You can set a pointer to a mutex_lock in struct video_device. Usually this
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will be either a top-level mutex or a mutex per device node. By default this
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lock will be used for unlocked_ioctl, but you can disable locking for
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selected ioctls by calling:
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The V4L core provides optional locking services. The main service is the
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lock field in struct video_device, which is a pointer to a mutex. If you set
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this pointer, then that will be used by unlocked_ioctl to serialize all ioctls.
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void v4l2_disable_ioctl_locking(struct video_device *vdev, unsigned int cmd);
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If you are using the videobuf2 framework, then there is a second lock that you
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can set: video_device->queue->lock. If set, then this lock will be used instead
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of video_device->lock to serialize all queuing ioctls (see the previous section
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for the full list of those ioctls).
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E.g.: v4l2_disable_ioctl_locking(vdev, VIDIOC_DQBUF);
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The advantage of using a different lock for the queuing ioctls is that for some
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drivers (particularly USB drivers) certain commands such as setting controls
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can take a long time, so you want to use a separate lock for the buffer queuing
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ioctls. That way your VIDIOC_DQBUF doesn't stall because the driver is busy
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changing the e.g. exposure of the webcam.
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You have to call this before you register the video_device.
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Of course, you can always do all the locking yourself by leaving both lock
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pointers at NULL.
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Particularly with USB drivers where certain commands such as setting controls
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can take a long time you may want to do your own locking for the buffer queuing
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ioctls.
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If you want still finer-grained locking then you have to set mutex_lock to NULL
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and do you own locking completely.
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It is up to the driver developer to decide which method to use. However, if
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your driver has high-latency operations (for example, changing the exposure
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of a USB webcam might take a long time), then you might be better off with
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doing your own locking if you want to allow the user to do other things with
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the device while waiting for the high-latency command to finish.
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If a lock is specified then all ioctl commands will be serialized on that
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lock. If you use videobuf then you must pass the same lock to the videobuf
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queue initialize function: if videobuf has to wait for a frame to arrive, then
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it will temporarily unlock the lock and relock it afterwards. If your driver
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also waits in the code, then you should do the same to allow other processes
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to access the device node while the first process is waiting for something.
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If you use the old videobuf then you must pass the video_device lock to the
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videobuf queue initialize function: if videobuf has to wait for a frame to
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arrive, then it will temporarily unlock the lock and relock it afterwards. If
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your driver also waits in the code, then you should do the same to allow other
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processes to access the device node while the first process is waiting for
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something.
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In the case of videobuf2 you will need to implement the wait_prepare and
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wait_finish callbacks to unlock/lock if applicable. In particular, if you use
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the lock in struct video_device then you must unlock/lock this mutex in
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wait_prepare and wait_finish.
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wait_finish callbacks to unlock/lock if applicable. If you use the queue->lock
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pointer, then you can use the helper functions vb2_ops_wait_prepare/finish.
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The implementation of a hotplug disconnect should also take the lock before
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calling v4l2_device_disconnect.
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The implementation of a hotplug disconnect should also take the lock from
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video_device before calling v4l2_device_disconnect. If you are also using
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video_device->queue->lock, then you have to first lock video_device->queue->lock
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followed by video_device->lock. That way you can be sure no ioctl is running
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when you call v4l2_device_disconnect.
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video_device registration
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-------------------------
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