[linux-dvb] Re: DVB + SATA

[Manu Abraham <manu@kromtek.com>]

On Thursday 29 Jul 2004 4:29 pm, Johannes Stezenbach wrote:
> Tim wrote:
> > It appears that boards with the Intel SATA controller built in to the
> > south bridge don't have any problems.
> >
> > With the NF7-S and VP DVB-t, some fiddling with PCI latency settings
> > improves matters a little, but it is still unwatchable when recording. I
> > think the VisionPlus is a lost cause.
> >
> > I'm still trying to find a DVB-t card that is likely to work with the
> > NF7-S V2.0 and SATA. Any more comments? I'm thinking of shelling out for
> > a DVICO card in the hope that it will be more reliable.
>
> There's the possibility that the power supply isn't
> stable enough. DVB frontends are quite sensitive in
> that area.
>
> Another possibility which was discussed recently on lkml is
> that large IDE DMA transfers are a source of high irq latency
> (i.e. the DVB card misses some irqs). But I guess the
> DVB driver would spit out error messages in this case.
> You could try to lower max_s from 2048 to e.g. 128 in
> linux/drivers/ide/ide-disk.c:idedisk_setup() to find out.
>

	Before making a final conclusion, why not check up the connection to the LNB 
? There can be problems on bad connectors as well -- if the shield does not 
have a good connection with the connector. Earlier somebody had a similar 
problem with the same symptom, the only difference in that case was, when the 
machine was getting heated up.

		The entire cable run could be checked up for possible problems before 
jumping into conclusions. 

		I had CRC errors when i had bad splitters. Just make sure it is the IDE DMA 
controller itself. I had problems when i tried to reduce latency to less than 
64. Eventhough Twinhan suggests 256.

		One more case is there, the vision plus cards are claimed to have problems 
with some VIA chipsets and some Triton chipsets by the manufacturer itself. I 
don't know which motherboards do carry these chipsets. What info i got was it 
was due to the bad timing on the chipset.


Regards,
Manu

> Johannes