[pvrusb2] sysfs, usdev and udevinfo

[xavier.gnata at free.fr]

Selon Mike Isely <isely at isely.net>:

> On Mon, 31 Mar 2008, xavier.gnata at free.fr wrote:
>
> > Hi,
> >
> > I'm a very happy pvrusb2 user :) but I have a question:
> >
> > I would like to write an udev rule to set the user permission on /sys
> pvrusb2
> > related directory.
> >
> > http://reactivated.net/writing_udev_rules.html tells me to type
> > udevinfo -a -p $(udevinfo -q path -n /dev/video3) to find some relevant
> info
> > about the device.
> > Unfortunately, I get only that:
> >
> >   looking at device '/devices/virtual/video4linux/video3':
> >     KERNEL=="video3"
> >     SUBSYSTEM=="video4linux"
> >     DRIVER==""
> >     ATTR{dev}=="81:3"
> >     ATTR{name}==""
> >
> >   looking at parent device '/devices/virtual/video4linux':
> >     KERNELS=="video4linux"
> >     SUBSYSTEMS==""
> >     DRIVERS==""
> >
> >   looking at parent device '/devices/virtual':
> >     KERNELS=="virtual"
> >     SUBSYSTEMS==""
> >     DRIVERS==""
> >
> > Nothing useful to tell udev that it is my TVcard and not another
> video4linux
> > device :(
> >
> > If I do the same on video1 (integrated webcam), I get a lot of info:
> >
> >   looking at device
> > '/devices/pci0000:00/0000:00:1d.7/usb7/7-6/7-6:1.0/video4linux/video0':
> >     KERNEL=="video0"
> >     SUBSYSTEM=="video4linux"
> >     DRIVER==""
> >     ATTR{dev}=="81:0"
> >     ATTR{name}=="Laptop Integrated Webcam"
> >
> > ATTR{name}=="Laptop Integrated Webcam" is enough to write an udev rule.
> > ATTRS{vendor}=="0x8086" or ATTRS{device}=="0x2836" could also be used.
> >
> > Why do we get nothing with pvrusb2 ?
>
> Hmm, interesting.  I've never studied this.  I will have to figure out
> how that name attribute can be injected.  Right now I don't do anything
> "special" to get udev to act, and have been assuming that V4L triggers
> this as part of the process to register the device node.
>
> If someone can answer the "how" to do that before I figure out, I'll be
> happy to add that to the driver.  It would also be good to get the
> device's serial number in there as well (perhaps as another attribute).
>
>
> >
> > /etc/udev/rules.d# modinfo pvrusb2
> >
> > filename:
> >
> /lib/modules/2.6.24-12-generic/kernel/drivers/media/video/pvrusb2/pvrusb2.ko
> > license:        GPL
> > description:    Hauppauge WinTV-PVR-USB2 MPEG2 Encoder/Tuner
> > author:         Mike Isely <isely at pobox.com>
> > srcversion:     E72D8CD6A2CD1A14A1C9C05
>
> Yeah, that's all stuff compiled into the module itself.  I doubt that is
> visible to anything in-kernel at run time after the driver has been
> loaded and bound.
>
> >
> > Cheers,
> > Xavier
>
> I remember you from the very very beginning of this project.  Good to
> see you're still around :-)
>
>   -Mike


It looks like it has something to do with /usr/share/hwdata/usb.ids but for
instance there is no mention of "Laptop Integrated Webcam" in this ubs.ids.
I even fail to understand where this "Laptop Integrated Webcam" comes from.
I should read this small webcam driver sources in detail to find out what is
going on here...

Xavier