[OpenWrt-Devel] [PATCH v2 1/2] ramips: second spi device on rt5350

[jonsmirl at gmail.com]

On Tue, Aug 19, 2014 at 3:48 PM, Álvaro Fernández Rojas <noltari at gmail.com>
wrote:

> El 19/08/2014 21:43, jonsmirl at gmail.com escribió:
> > How is the clock speed wrong?
>
> The lowest speed the RT5350 SPI controller can achieve is System Clock /
> 128.
> System Clock = 120MHz
> Lowest SPI Clock = 120MHz / 128 = 937.5KHz
>
> However, the MMC/SD cards need to be initialized at 100-400KHz.
>

This might work... Put the SPI pins into GPIO mode. Use the kernel bit-bang
support for SPI to initialize the card.  Then go back to high speed mode.

-- 
Jon Smirl
jonsmirl at gmail.com
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