Re: [RFC/PATCH] sysfs'ify video4linux

From: Gerd Knorr (
Date: Wed Jul 16 2003 - 03:44:48 EST

> > * some usb webcam drivers (usbvideo.ko, stv680.ko, se401.ko
> > and ov511.ko) use the video_proc_entry() to add additional
> > procfs files. These drivers must be converted to sysfs too
> > because video_proc_entry() doesn't exist any more.
> I'd be glad to do this work once your change makes it into the core. Is
> there any need for these drivers to export anything through sysfs now
> instead of /proc? From what I remember, it only looked like debugging
> and other general info stuff.

IIRC some tuning / debugging / info stuff, the drivers should work just
fine without. Temporarely disableling that wouldn't be a big issue

> So dev should point to the dev of the video class device?

Exactly. videodev.o will put that into class_device->dev which in turn
will produce these symlinks:

eskarina kraxel /sys/class/video4linux/video0# ll device
lrwxrwxrwx 1 root root 53 Jul 15 17:20 device -> ../../../devices/pci0000:00/0000:00:06.0/0000:02:07.0/

> > Comments?
> You _have_ to set up a release function for your class device. You
> can't just kfree it like I think you are doing, otherwise any users of
> the sysfs files will oops the kernel after the video class device is
> gone.

class_device_unregister() is called from video_unregister_device() which
looks fine to me. Or do you talk about something else?

> Other than that, how about exporting the dev_t value for the video
> device? Then you automatically get udev support, and I don't have to go
> add it to this code later :)

Do you have a pointer to sample code for that?


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This archive was generated by hypermail 2b29 : Wed Jul 23 2003 - 22:00:23 EST