[linux-dvb] Re: New DVB driver release 1.0.0-pre1

[Oliver Endriss <o.endriss@gmx.de>]

emard@softhome.net wrote:
> ...
> So, such queue should collect all DEBI writes
> (because they arrive asynchronous, parallel and overlap)
> and serialize them over DEBI bus. But it's not so simple
> as the printer:
>
> Second problem is half duplex. DEBI is bidirectional
> bus, but because of firmware simplicity/stability it
> probably has to be half-duplex. When send is going on,
> receive must wait and vice versa.
>
> To get rid of oops and race conditions, the half-duplex
> DEBI queue has to be introduced.
>
> Queue should serialize continuous multy-byte DEBI
> message packets and feed them to debi bus one by one
> message. There can be only one, non-reentrant function
> which should service DEBI transfers from all sources:
> user-space and kernel-interrupt-space.

Couldn't we use the second Register Programming Sequencer (RPS) of the 
SAA7146A to handle the DEBI stuff?
This way it might be possible to get rid of busy-waiting in 
wait_for_debi_done(), which is really ugly when vdr is running in 
time-shift mode. I haven't looked at this in detail but it might be 
possible. Any comments?

Oliver




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