[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

Re: How to achieve a long burst <OFFTOPIC>?

Dear all!

> Unfortunately, it appears that the bridge chips on PC motherboards do
> not implement DMA engines.  Therefore it falls to the peripherals to
> implement DMA.. which also mandates they must be capable of 
> becoming the PCI bus master. 

Let me take this as a opportunity to answer a question:

What's needed to become a PCI bus master?
We have a processor board that hides behind a 
non-transparent Intel 21554 bridge, therefore 
seen as a device from the host CPU. The bridge
cannot be arbiter of the primary bus the host 
CPU is on but supports the "Master Enable"-Bit
on this side. Would it be sufficient to set this
bit to enable the "Slave-CPU" on the secondary side
of the bridge to do Busmaster-DMA?

Thanks a lot - an sorry to be offtopic.