[U-Boot-Users] [rfc] new spiflash subsystem

[Haavard Skinnemoen]

On Tue, 29 Jan 2008 08:35:50 +0100
"Ulf Samuelsson" <ulf.samuelsson at atmel.com> wrote:

> > Your code does not support DMA transfers, while the current dataflash code
> > runs DMA up to 50 Mbps.  
> 
> so ?  the point of u-boot is to do everything in PIO mode.
> 
> ==> This is not how the dataflash support is implemented in U-Boot today.  
>         Current implementation is using DMA.

Current implementation is also AT91-only, which is a design flaw that
is much worse than anything in Mike's approach.

That said, I think the low-level SPI API should make it possible for a
low-level driver to do DMA. The proposed byte-at-a-time API does not
allow this, while the existing spi_xfer() interface in include/spi.h
does, assuming the buffers are properly aligned.

Haavard