PERFORCE change 112700 for review

[Bernd Walter]

On Wed, Jan 10, 2007 at 06:56:56AM +0000, Warner Losh wrote:
> http://perforce.freebsd.org/chv.cgi?CH=112700
> 
> Change 112700 by imp at imp_lighthouse on 2007/01/10 06:56:33
> 
> 	MF FreeBSD-tsc-6: slow down spi bus enough to make the dataflash
> 	parts reliable on read.  MCK / 2 is too fast.  I think MCK / 4
> 	would work too, but MCK / 20 was rock solid.
> 	
> 	I think this works in the boot loader because we're running with
> 	the caches off, slowing things down, but I am actually a bit
> 	baffled.  Maybe I just have a bad board...

Mmm - you have a 'D' type flash, which allows 33MHz in low frequency
mode.
My 'C' type allows 33MHz as well.
So in theory MCK/2 (30MHz) should work.
Older 'B' type max out at 20MHz.
I've just used flash access in the bootloader however.

> Affected files ...
> 
> .. //depot/projects/arm/src/sys/arm/at91/at91_spi.c#16 edit
> 
> Differences ...
> 
> ==== //depot/projects/arm/src/sys/arm/at91/at91_spi.c#16 (text+ko) ====
> 
> @@ -115,7 +115,7 @@
>  	WR4(sc, SPI_MR, (0xf << 24) | SPI_MR_MSTR | SPI_MR_MODFDIS |
>  	    (0xE << 16));
>  
> -	WR4(sc, SPI_CSR0, SPI_CSR_CPOL | (4 << 16) | (2 << 8));
> +	WR4(sc, SPI_CSR0, SPI_CSR_CPOL | (4 << 16) | (20 << 8));
>  	WR4(sc, SPI_CR, SPI_CR_SPIEN);
>  
>  	WR4(sc, PDC_PTCR, PDC_PTCR_TXTDIS);

-- 
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