[linux-dvb] Re: Could HPS/DMA1 be used for budget DMA...?

[Jamie Honan <jhonan@optusnet.com.au>]

On Sun, Oct 26, 2003 at 07:58:26PM +0100, Robert Schlabbach wrote:
> Hi,
> 
> I've been wondering if the "sensitivity" of budget-card DMA transfers would
> be lessened if the HPS and video DMA1 of the SAA7146A was used for
> transferring the MPEG-2 Transport Stream instead of the current BRS/DMA3
> path (maybe HPS/DMA1 is less bugged than BRS/DMA3...).

I can't speak directly to the question you pose here, but I do have
a suggestion.

I saw your and Jon Burgess's posts on this problem going back some time
now, and thought this was my problem with a budget terrestial card
(new Nova-t, under budget-ci).

I had the devil's own problem using vdr and this card, using my
DST there were no problems.

I tried Jon's hack (detecting errors at the end and middle of buffers)
and it didn't trip debugging detecting code once.

I tried your burst suggestions, I added code so the irq rate
could be changed from 9 blocks to whatever. The last actually made
things worse, when changed to a lower value.

At no stage could I see any corruption, I simply concluded that packets
must have been dropped.

Then I tried using mplayer instead of vdr, to my astonishment the
picture was absolutely perfect.

I think it is possible for an application to interact with the driver
in a strange way.

As a suggestion, or sanity check, all I can say is make sure the
problem is not at a higher level. Check with a couple of apps.

Sometimes I've looked in the wrong place for days.

Jamie


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