Subject: Re: SD card over (xilinx_)SPI, timeout error while CID

From: Lorenz Kolb <[email-masked]>
Date: Mon, 08 Jun 2009 17:14:45 +0200

Peter Korsgaard wrote:
>>>>>> "Joachim" == Joachim Foerster <[email-masked]> writes:
>>>>>>             
>
> Hi,
>
>  Joachim> Any hints? Does anybody use SD card support with
>  Joachim> mmc_spi+xilinx_spi ?
>
> I don't, but have you compared the spi signals on a scope in the 2
> setups? Is timing significantly different?
>
>   
Hi,

we just tried to find differences for the timing with the oszi:

Here are to screenshots taken from the initial first few data bytes that are
communicated. At least at that time there does not seem to be any timing 
issue.

2.6.26 using arch ppc and virtex-devices:

http://img145.imageshack.us/img145/9662/2626virtexdevices.jpg

2.6.29.4 using arch powerpc:

http://img145.imageshack.us/img145/9847/2629devtree.jpg

For explanation:

yellow = chan 1 = MOSI = trigger
green = chan 2 = chipselect not
blue = chan 3 = clock
red = chan 4 = MOSI

Looks like we're gonna have to switch to a logic analyzer
(with spi-mode sdcard analyzing support) as we cannot see any differences
in the short timeframe our oszi does measure, though checking the timing
does not look too promising.

We even configured the Xilinx-SPI core to go down to ~780 kHz just to be 
safe,
did not help either.

Regards,

Lorenz