[linux-dvb] Re: Nova card drops packets...

[<mocm@metzlerbros.de>]

Vincent Legoll writes:
 > > The IRQ for the end of data transfer comes before the DMA
 > > is done. So we have to wait in the IRQ until DMA is finished.
 > 
 > How could the card send DMA completion IRQ before DMA
 > has finished ?
 > 

We are using the field ID interrupt on port B of the saa7134 to see if
a certain amount of data is written. Essentially, the TS packets are
handled as video data, with a synch on the 0x47 of the TS packet
header. Actually, the first step of getting the budget cards to run
was having a picture of the TS packets on the screen using tuxview.


 > That definitely sounds like broken hardware and / or firmware
 > to me...
 > 

There is no firmware and the hardware and its design is probably price
optimized, i.e. using saa7134 as a well known chip for the pci bridge
and using the high bandwidth video input and DMA to transfer the TS data. 

 > BTW waiting inside IRQ handler does not sound like a good
 > real solution to this... perhaps we should poll the device at
 > regular intervals instead and ask if DMA has finished...
 > or something like that...

Already done.

Marcus



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