[U-Boot-Users] RFC: Some improvements for the FPGA subsystem

[w.wegner at astro-kom.de]

Hi,

On 12 Nov 2007 at 10:45, Matthias Fuchs wrote:

> > I have one wish on my list:
> ... you haven't seen my wishlist :-)

:-))

> I was in a similar situation some time before. Our PMC440 board (patches have
> been posted yesterday) uses a Spartan3E FPGA that is programmed in slave serial 
> mode. I started with download time about 13 seconds (!!!). The main reason 
> is the extensive use of callbacks by the FPGA subsystem. Then updated the boot 
> code to use U-Boot's slave parallel implementation to boot the FPGA still in
> slave serial mode. My write-data-byte function just shifts out the byte bit by bit.
> This improved the download time to about 3 seconds. The last step was to
> enable the cache for the 440 CPU. This speeds things up to an acceptable level.

I currently have around 3 seconds for a partially filled XC3S4000 on my
MCF5373L (240 MHz) with cache enabled. This is almost below my pain
limit, which is why I did not yet take the effort to debug the SPI load any
further.

> If you already have something it might be a good idea to share your work
> with us. I think this is independent from what my patch does at the moment.

The usual problem: it is a bit difficult to extract only this as a clean patch...

I will see what I can do, but it can take some days.

> Matthias

Regards,
Wolfgang