[mythtv-users] OT? /proc/pci

[Sean Covel]

Sean Covel wrote:

> Tim Tait wrote:
> 
>> Jason Kraftcheck wrote:
>>
>>> Joel Anderson wrote:
>>>  
>>>
>>>> Marc-David Meijer wrote:
>>>>
>>>> As I understand it, PCI devices don't depend on IRQs anyway.  They use
>>>> interrupt "channels", and IRQs are just kept around to keep legacy 
>>>> stuff
>>>> happy.  You will often see many devices appear to "share" the same IRQ,
>>>> but it is not really true since IRQ's can't really _be_ shared.
>>>>
>>>> Someone please comment if I haven't explained this correctly.  It's a
>>>> simplification, but it basically means that IRQ issues shouldn't come
>>>> into play unless you have some legacy hardware in the system also.
>>>>   
>>>
>>>
>>> I'm no expert either, but I think they are actually "shared".  The
>>> interrupt handler must poll each device by invoking the interrupt
>>> handler in the driver for each device sharing the interrupt.  Thus
>>> there's a slight performance loss when sharing interrupts, and also the
>>> possibility for buggy drivers to interfere with each other.
>>>  
>>>
>> Newer PCI devices support "Message Signalled Interrupts" which use no 
>> physical IRQ line, but instead write a pre-configured value to the PCI 
>> bridge inbound MSI register to cause a unique interrupt. I can't say 
>> for sure the 250MCE actually does that (or that the driver sets it up 
>> that way) but it is possible.  People have commented eslwhere on the 
>> list that it appears the 250MCE needs a PCI Rev 2.2 compliant 
>> motherboard, so you might want to check your  mobo docs out and see if 
>> it complies.
>>
> 
> Tim,
> 
> That's probably it.  The mobo of my backend box is OLD.  Its running 2 
> PIII 600Mhz Slot 1 procs and the on-board IDE is only UDMA33.  OLD!  My 
> "play" machine is running 2 PIII 1.2Mhz Server procs.  Guess its time to 
> swap the MythTv backend to the "play" machine.
> 
> The "play" machine does recognize the card, now I need to spend the time 
> to get IVTV working on it.  I'm sure it will work now that lspci 
> recognizes the card.
> 
> Thanks for all your help guys!!!
> 
> Sean
> 
HELP!!!

What is this card anyway?

0000:00:0c.0 Multimedia video controller: Conexant Winfast TV2000 XP 
(rev 05)
         Subsystem: Hauppauge computer works Inc.: Unknown device 2801
         Flags: bus master, medium devsel, latency 32, IRQ 16
         Memory at dd000000 (32-bit, non-prefetchable)
         Capabilities: [44] Vital Product Data
         Capabilities: [4c] Power Management version 2

0000:00:0c.1 Multimedia controller: Conexant: Unknown device 8801 (rev 05)
         Subsystem: Hauppauge computer works Inc.: Unknown device 2801
         Flags: bus master, medium devsel, latency 32, IRQ 16
         Memory at de000000 (32-bit, non-prefetchable)
         Capabilities: [4c] Power Management version 2

0000:00:0c.2 Multimedia controller: Conexant: Unknown device 8802 (rev 05)
         Subsystem: Hauppauge computer works Inc.: Unknown device 2801
         Flags: bus master, medium devsel, latency 32, IRQ 16
         Memory at df000000 (32-bit, non-prefetchable)
         Capabilities: [4c] Power Management version 2

IVTV loads, but I never get the correct video device /dev/video0.  I was 
under the assumption that ivtv created the devices?

Sean