On Thu, 2009-06-04 at 11:18 +0200, Laurent Pinchart wrote:
> Hi,
>
> On Thursday 04 June 2009 06:20:07 figo.zhang wrote:
> > The function video_register_device() will call the
> > video_register_device_index(). In this function, firtly it will do some
> > argments check , if failed,it will return a negative number such as
> > -EINVAL, and then do cdev_alloc() and device_register(), if success return
> > zero. so video_register_device_index() canot return a a positive number.
> >
> > for example, see the drivers/media/video/stk-webcam.c (line 1325):
> >
> > err = video_register_device(&dev->vdev, VFL_TYPE_GRABBER, -1);
> > if (err)
> > STK_ERROR("v4l registration failed\n");
> > else
> > STK_INFO("Syntek USB2.0 Camera is now controlling video device"
> > " /dev/video%d\n", dev->vdev.num);
> >
> > in my opinion, it will be cleaner to do something like this:
> >
> > err = video_register_device(&dev->vdev, VFL_TYPE_GRABBER, -1);
> > if (err != 0)
> > STK_ERROR("v4l registration failed\n");
> > else
> > STK_INFO("Syntek USB2.0 Camera is now controlling video device"
> > " /dev/video%d\n", dev->vdev.num);
>
> What's the difference ? (err != 0) and (err) are identical.
>
> Best regards,
>
> Laurent Pinchart
yes, it is the same, but it is easy for reading.
btw, see driver/media/video/ov511.c (line 5853):
if (video_register_device(ov->vdev, VFL_TYPE_GRABBER,
unit_video[i]) >= 0) {
break;
}
it would not return a positive number,i think. pls see my other path:
http://www.spinics.net/lists/linux-media/msg06140.html
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