From mboxrd@z Thu Jan 1 00:00:00 1970 Message-ID: <3E772F39.1090303@embeddededge.com> Date: Tue, 18 Mar 2003 09:37:45 -0500 From: Dan Malek MIME-Version: 1.0 To: "Penn, John" Cc: linuxppc-embedded@lists.linuxppc.org Subject: Re: 8250 idma problem - cache? References: Content-Type: text/plain; charset=us-ascii; format=flowed Sender: owner-linuxppc-embedded@lists.linuxppc.org List-Id: Penn, John wrote: > Much better!! Cool. > So for receiving, local bus to system memory, I assume > I need to set DGBL? Yes. > What would be a wise choice? Using system memory? The system memory could be a better choice depending upon the speed of the device since both the device and local memory share the same bus. It would just remove some contention and latency. There are other system architecture considerations but usually pipelining the DMA like this is a performance advantage. > ... Should I be able to use DPRAM for the BDs and system > memory for the buffers? Yes. Just ensure the address or whatever indicators are used to point the parameter blocks to the BDs in the DPRAM (or local bus) are set correctly. Also verify that the BDs can reside in DPRAM, IIRC some peripherals or configurations don't allow it. -- Dan ** Sent via the linuxppc-embedded mail list. See http://lists.linuxppc.org/