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V4L/DVB (10988): v4l2-dev: use parent field if the v4l2_device has no parent set.

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Normally the parent device of v4l2_device is used as the video device
node's parent. But if it was not set, then use the parent field in the
video_device struct.

This is needed in the cx88 driver, which has one core v4l2_device but
creates multiple pci devices (one each for raw and mpeg video).

So you cannot associate the core v4l2_device with a particular PCI device,
but you can do that for each video_device.

Signed-off-by: Hans Verkuil <hverkuil@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>
This commit is contained in:
Hans Verkuil 2009-03-13 10:03:04 -03:00 committed by Mauro Carvalho Chehab
parent afd96668d8
commit 005759613b
2 changed files with 12 additions and 2 deletions
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12
Documentation/video4linux/v4l2-framework.txt
View file

@ -91,7 +91,8 @@ NULL, then you *must* setup v4l2_dev->name before calling v4l2_device_register.
The first 'dev' argument is normally the struct device pointer of a pci_dev,
usb_device or platform_device. It is rare for dev to be NULL, but it happens
with ISA devices, for example.
with ISA devices or when one device creates multiple PCI devices, thus making
it impossible to associate v4l2_dev with a particular parent.
You unregister with:
@ -414,6 +415,15 @@ You should also set these fields:
- ioctl_ops: if you use the v4l2_ioctl_ops to simplify ioctl maintenance
(highly recommended to use this and it might become compulsory in the
future!), then set this to your v4l2_ioctl_ops struct.
- parent: you only set this if v4l2_device was registered with NULL as
the parent device struct. This only happens in cases where one hardware
device has multiple PCI devices that all share the same v4l2_device core.
The cx88 driver is an example of this: one core v4l2_device struct, but
it is used by both an raw video PCI device (cx8800) and a MPEG PCI device
(cx8802). Since the v4l2_device cannot be associated with a particular
PCI device it is setup without a parent device. But when the struct
video_device is setup you do know which parent PCI device to use.
If you use v4l2_ioctl_ops, then you should set either .unlocked_ioctl or
.ioctl to video_ioctl2 in your v4l2_file_operations struct.

2
drivers/media/video/v4l2-dev.c
View file

@ -395,7 +395,7 @@ int video_register_device_index(struct video_device *vdev, int type, int nr,
vdev->vfl_type = type;
vdev->cdev = NULL;
if (vdev->v4l2_dev)
if (vdev->v4l2_dev && vdev->v4l2_dev->dev)
vdev->parent = vdev->v4l2_dev->dev;
/* Part 2: find a free minor, kernel number and device index. */