Re: [PATCH]V4L:some v4l drivers have error for video_register_device

["figo.zhang" <figo.zhang@kolorific.com>]

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