Re: DMA transfer problem

["Peter Marek" <peter.marek@marekmicro.de>]

Hi,

 

you should try to use MWI and MRL commands for the DMA. The host bridge will make use of these commands and optimize cache snooping and SDRAM accesses.

This will result in higher PCI performance.

 

regards,

 

Peter Marek
General Director
MarekMicro GmbH
tel.: 049-9621-9732-110
fax: 049-9621-9732-199
www.marekmicro.de

----- Original Message -----

From: Traian - Pulse Instruments

To: pci-sig@znyx.com

Sent: Wednesday, November 21, 2001 12:04 AM

Subject: DMA transfer problem

Hi,

 

I am having a hard time getting my DMA transfers to run at a reasonable speed.

I have a GT64120A chip on my CPCI board that is attempting to transfer data

to the CPU's DRAM. The problem is that about half the time it does a burst

transfer, and the other half of the time, it receives TargetDisconects and retries

the transfer until it finally gets it through.

 

I tried with several CPUs: MOTOROLA, Triems, they all seem to do the same.

I do not have (obviously) much experience mastering the bus, so am asking for help from the experts.

Any idea why this is happening, and what could be done to alleviate the problem?

I do have a state/waveform - diagram available by request.

 

Traian Mitrache
Pulse Instruments    (p) 310-515-5330
1234 Francisco St, Torrance, CA 90502