[linux-dvb] Re: Network: a new hope

[Emard <emard@softhome.net>]

> >Sorry, I haven't followed this issue right from the start: Does it occur
> >_only_ on budget class cards with the SAA7146A on it?
> 
> Only on Budget cards.

Is there some other full-TS card like budget that is know to work well with
DMA? (Maybe I can try it too)

> Yes, as you probably know this is called "graceful recovery" and makes 
> perfect sense for video data: if the data cannot be delivered (for 
> example because the PCI bus is hogged by something else and the FIFOs 
> overflow) then the saa7146 throws away the data and advances the pointer 
> until the bus becomes free again.

I have seen lots of this on one of my previous machine, with more disk
load then the picture gets some kind of digital 'persistency' similar to
ancient green monitors (see matrix) when the phospors on the screen are 
glowing longer after the electron beam is gone, moving things like cursors
leave trains. So here a horizontal lines of the video picture tend
to persist, and moving objects leaving interesting digital 'trails'. 

> Of course this is bad for non-video data, but the saa7146's BRS wasn't 
> designed to transport real data anyway...

Yeah, they should have blessed it with larger output FIFO, when they provided 
3 simultaneous high speed TS feed ports (and now we have hard time getting 
just 1 of them working correctly ...)

> Good idea. This will show if the system suffers from PCI hogging issues 
> or not.

I now have onbard chipset with PCI 'switch' that does good asynchronous PCI, 
not letting other PCIs to interfere


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