[Open-graphics] Byte twising

[Timothy Normand Miller]

On Dec 9, 2007 4:46 PM,  <ndownes at tampabay.rr.com> wrote:
> I was going to comment on this.  By integrating PCI onto the core we are limiting options for the future.  What I would suggest is using a general chip interface, such as Wishbone, so that in the future it would be easier to replace PCI with AGP, PCIe or even integrate it into a SoC.
>

I really don't like wishbone.  I've commented on this elsewhere.  You
do, in any case, have an excellent point, and the solution is still
kinda up in the air.

For PCIe, our short-term solution is to add a PCIe-1x to PCI-66
bridge.  The two have comparable maximum throughput.  The only
drawback will be the added latency through the interface chip.  With
DMA, that latency will be negligible.  For OGA1, we have no plans for
anything wider than PCIe 1x because we cannot take advantage of it
properly.  We'll reserve that for a later generation.


-- 
Timothy Normand Miller
http://www.cse.ohio-state.edu/~millerti
Open Graphics Project