Date: Wed, 23 Aug 1995 11:03:19 -0700 (PDT) From: "Rodney W. Grimes" <rgrimes@gndrsh.aac.dev.com> To: james@miller.cs.uwm.edu (Jim Lowe) Cc: current@freebsd.org, se@ZPR.Uni-Koeln.DE, tinguely@plains.nodak.edu Subject: Re: Matrox Meteor Video Capture Card Driver Message-ID: <199508231803.LAA09805@gndrsh.aac.dev.com> In-Reply-To: <199508231537.KAA26926@miller.cs.uwm.edu> from "Jim Lowe" at Aug 23, 95 10:37:28 am
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> > > From: "Rodney W. Grimes" <rgrimes@gndrsh.aac.dev.com> > > > > The NCR runs it's firmware from the host memory, try cranking the PCI > > latency timer down for the NCR card and see if that helps. (This is > > in the PCI bios setup screen). Depending on motherboards (I happen > > to know what ``Triton'' board Jim just tried this in) there maybe > > 1 setting for all slots, or each slot may have it's own setting. > > > > Either way, crank it down to about 40 (default should be 80). > > > > From: se@zpr.uni-koeln.de (Stefan Esser) > > > > Did you try lower values of the "PCI Latency > > Timer" of the slot the Matrox has been put in ? > > > > (This timer determines the number of bus clocks > > a PCI card may claim ownerchip of the PCI bus, > > if another card wants to start a transfer. > > The NCR executes its instruction stream from > > host RAM, and it may get into trouble if it > > can only get another instruction every 10us ...) > > > > A latency timer setting of some 0x20 for the > > matrox should allow the NCR to access the bus > > once per micro second. Guess this is a good > > value ... > > > > (The latency timer doesn't force the PCI device > > to give up bus ownership if there is no request > > from another device and thus doesn't slow down > > the Matrox unless it makes the NCR starve ...) > > > > I tried lowering the PCI latency timer from 80 to 40, then to 20, then 1, > then 0. It helped me get a few frames at 640x480 before the machine > hung. I also tried disabling the cpu to pci burst mode. > > I have been running the meteor in a machine with and adaptec controller > for 5 days and it never hung. I am still not sure why the machine > hangs with the ncr controller. I am affraid to get a real picture of just what is going on here is going to require the use of a PCI bus analyzer :-(. I don't happen to have one of them, double :-(, :-(. -- Rod Grimes rgrimes@gndrsh.aac.dev.com Accurate Automation Company Reliable computers for FreeBSD
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