From mboxrd@z Thu Jan 1 00:00:00 1970 Reply-To: From: "Allen Curtis" To: "Arto Vuori" Cc: Subject: RE: 8260 IDMA experience? Date: Mon, 3 Jun 2002 06:20:54 -0700 Message-ID: MIME-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" In-Reply-To: <3CFB620E.9F8643EB@ssh.com> Sender: owner-linuxppc-embedded@lists.linuxppc.org List-Id: > I have been using IDMA to transfer data between kernel memory and a > FPGA. I also did some testing with memory-to-memory transfers and i > didn't find them to be worth the trouble. Performance ain't that great. > You probably get more speed by copying with your CPU, though you might > avoid some cache trashing. So it works but it may not be as fast as a memcpy(). Sounds like more testing is required to determine the overall benefit of freeing the processor. > I did also notice that when i am doing memory-to-peripheral (or > vice-versa) transfers, IDMA corrupts simultaneous Ethernet traffic > unless IDMA is set to low-priority mode. Same might apply for > memory-to-memory transfers. What 8260 chip revision are you using? I have found lots of problems when rev A processors but rev C has been much better. ** Sent via the linuxppc-embedded mail list. See http://lists.linuxppc.org/