[libre-riscv-dev] Wishbone Arbiter

[Jacob Lifshay]

On Sun, Jan 26, 2020, 18:04 Michael Nolan <mtnolan2640 at gmail.com> wrote:

> > a temporary video blip is much better than crashing due to corrupted ram.
>
> I think it's not unreasonable to have the display controller be a little
> tolerant of latency. Since the access pattern is very regular, having it
> prefetch into a buffer of $MAXLATENCY * $PIXELFREQUENCY pixels would be
> relatively straightforward. It would also mean the DRAM controller
> wouldn't have to worry about initiating a refresh right before the
> display controller initiates a read.
>

Yeah, I would consider having a sufficiently-sized FIFO be a basic
requirement of the scanout engine. the only spot where it's not needed is
if the video memory was multi-ported SRAM, with one port dedicated to
scanout, which is only feasible for really low resolutions (even 640x480 is
probably too high).

Jacob