[mythtv-users] OT? /proc/pci
Sean Covel
seanecovel at comcast.net
Thu Jul 15 10:05:50 EDT 2004
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
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