[linux-dvb] Re: two concurrent DMAs with SAA7146?

["Robert Schlabbach" <robert_s@gmx.net>]

From: "Wolfgang Wegner" <wolfgang@leila.ping.de>
> The second problem is I am not sure if it is possible to completely
> bypass the HPS to get the new channel to DMA1.
>
> Did anybody try something like this yet? Any comments are highly
> welcome!

Yes, I have tried this - it doesn't work, because the HPS just cannot be
switched to "passthrough" mode. It will always "swallow" a few bytes,
corrupting the transport stream. See here:

http://linuxtv.org/mailinglists/linux-dvb/2003/10-2003/msg00548.html

I solved my problem by discovering that BRS/DMA3 is not bugged after all -
it only doesn't like switching the DMA MMU page tables on the fly.

So two concurrent transport stream DMA channels are not possible with the
SAA7146A, because you only have one BRS to use for DMA.

Regards,
--
Robert Schlabbach
e-mail: robert_s@gmx.net
Berlin, Germany