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Subject: Re: X5 dual boot

Re: X5 dual boot

From: Linus Nielsen Feltzing <linus_at_haxx.se>
Date: 2006-05-02

RaeNye wrote:
> Since the OF relies on what the preloader did.

Yes, we must make sure that we don't mess it up for the OF, but I think
the solution is to restore the registers before starting the OF.

> Serial vs. parallel?
> 1-bit transfer vs. 8-bit is 8 times slower, I guess.
> Same job done in less CPU work.

The difference is not parallel vs serial, I2C is a serial bus. The
difference is using the internal I2C controller vs "bit-banging". The
Cowon firmware uses the I2C controller, and we don't.

The X5 version of the Rockbox I2C driver is slow at the moment, so it
can be optimized. However, the performance is not important for the boot
loader.

> (The next totalliy unrelated topic would be DMA for ATA, but I leave this
> for later)

Yes, ATA DMA might speed things up a little, but not as much as you
might think. The assembler optimized ATA driver is pretty fast.

Linus
Received on Tue May 2 11:20:56 2006


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