[mythtv-users] Irratic PVR250 ivtv module load - Ubuntu

Douglas Peale Douglas_Peale at comcast.net
Tue Jul 13 18:31:45 UTC 2010


On 07/13/2010 03:02 AM, Mike McMullin wrote:
> On Tue, 2010-07-13 at 02:20 -0400, Andrew C. Stadt wrote:
>> On 13/07/2010 2:13 AM, Douglas Peale wrote:
>>> On 07/12/2010 09:49 PM, Douglas Peale wrote:
>>>    
>>>> On 07/12/2010 08:56 PM, John Drescher wrote:
>>>>      
>>>>>> It seems that everyone has their own opinion - some say udev rules
>>>>>> aren't so good, others swear by them.
>>>>>>   I don't see any ivtv named files in: /lib/udev/rules.d I would have
>>>>>> to figure out how it all works!
>>>>>>
>>>>>>          
>>>> I just spent a bunch of time trying to figure out how to get udev rules to work without success.
>>>>      
>>>    
>>>> The two symbolic links it is intended to create never show up. I have no idea what I am doing wrong.
>>>>      
>>> I found and fixed at least one error in my file, but I found that the instructions are misleading. Even though the system
>>> monitors the directory for changes, rules are only applied when the device is first recognized. the symbolic link "WebCam"
>>> showed up when I unplugged and plugged in the web cam.
>>>
>>> But it is all pointless. The tools that use the web cam won't let you enter a symbolic link. They display a list box of the
>>> devices they found, and the symbolic link does not show up. Those same tools are the ones that have problems when the device
>>> name changes. They all think that an ATI HDTV Wonder is just as good as a Microsoft LifeCam Cinema to use as a web cam.
>>> _______________________________________________
> 
> 
>> Never thought to try it, but once you can properly address a specific 
>> device in the udev rules, is it possible to force it to take a specific 
>> /dev/videoX ?
>>
>> Borrowing from my other post:
>>
>> SUBSYSTEM=="video4linux", ATTR{name}=="ivtv? encoder MPG", 
>> KERNELS=="0000:04:01.0", SYMLINK+="video0"
>> SUBSYSTEM=="video4linux", ATTR{name}=="ivtv? encoder MPG", 
>> KERNELS=="0000:04:02.0", SYMLINK+="video1"
>>
>> I also found must of the udev documentation to be very misleading and/or 
>> referring to obsolete revisions.
> 
> KERNEL=="video[0-9]*",ATTR{name}=="gspca",DRIVERS=="usb",NAME="video1"
> KERNEL=="video[0-9]*",ATTR{name}=="ivtv0 encoder
> MPG",DRIVERS=="ivtv",NAME="video4"
> 
>   These are actually two lines in
> my /etc/udev/rules.d/51-setup-video.rules file. My webcam does keep
> coming up as video0 but the pvr-150 is consistent as video4.
> 

Your webcam keeps coming up as video0 because video1 already exists. I don't believe the rules are applied until after the
kernel creates names for all the devices, and there is no way to swap a pair of existing names with udev rules.

In summary, while udev rules will allow you to create symbolic names, and MythTV will allow you to use those symbolic names,
most other applications won't let you use those symbolic names, so if one is trying to deal with a webcam which shows up as
/dev/video*, just like an analog TV tuner, udev rules does not help.


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