On Saturday 07 July 2007 16:58:36 John Schmitt wrote:
> On Saturday 23 June 2007 6:35:08 pm Rett D. Walters wrote:
> > Has any progress been made on supporting DMA on MCP55 (Nvidia
> > Nforce 550) chipsets? I am currently running a patched ivtv driver
> > to run my PVR 250 in PIO mode on a system with an AMD64x2 on an MSI
> > K9N Neo-F, and would like to not have to use 30% of the cpu to
> > record with Myth. I can offer up my system for testing fixes if
> > need be. As per the list archives I changed the source to use PIO
> > because I was getting DMA errors and no video.
>
> ...
>
> What are the alternative motherboards I could use to avoid this
> problem? Currently my system uses this one:
> http://www.newegg.com/product/product.asp?item=N82E16813136016
> It's a DFI C51PV-M2. I bought it because it had all the ports that I
> could ever want for my old CRT TV and it has connecters for flat
> screens (if I were ever to get one) and monitors and digital audio
> out as well as all the disk drive connectors.
>
> I just looked at newegg and I see GeForce 7050PV motherboards, but I
> don't know anything about them:
> http://www.newegg.com/Product/Product.aspx?Item=N82E16813138061
>
> Does DFI/nVidia know about this problem? Will there ever be a BIOS
> or any other resolution?
>
> Thanks for any input.
There is nothing I can do about it. DMA issues have always plagued the
cx23415/16 based cards. The cause is the buggy DMA engine of these
cards and that is not something I can do anything about. Depending on
your system, chipset and the phase of the moon you may or may not be
hit by these DMA problems. In general using RAID for your harddisks is
not recommended, also using a video card that uses normal RAM for its
video memory is a problem. After that your best bet is to replace your
motherboard. Intel chipsets seem to work best, at least I have seen few
if any issues with them. But many people also have no problems with ATI
and nVidia chipsets (including myself), so it does not seem to
be 'just' the chipset, but a combination of factors.
Note that the PVR500 seems to be less susceptible to these problems as
well: the DMA bridge on that card seems to isolate the cx23416 chips
from the DMA issues.
Note that these problems also occur under Windows, I know that Hauppauge
have modified their Windows driver to be able to very quickly reset the
DMA engine when they detect problems. Apparently this is very
complicated code and (not surprisingly) they won't release details on
it. I can't blame them for that, I'd probably do the same in their
position. Otherwise Hauppauge has been very supportive to me and linux
in general.
Regards,
Hans
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