On Thu, Apr 22, 2010 at 7:51 PM, Rob Emanuele rob@emanuele.us wrote:
Hi Henry & U-Boot Community,
I've been experiencing the same errors and frustration you have.
So I've been looking at this code and these patch sets for a day or two now. I've done that in conjunction with reading the SD card spec: http://www.sdcard.org/developers/tech/sdcard/pls/
I've come to the conclusion that this code as it stands will not work with any card that conforms to the SD Physical Layer Simplified Specification Version 2.0. This includes all SDHC cards and some non-HC cards that conform to version 2.0. I have a few 1GB cards that work just fine with the atmel_mci.c code on a 'G45 as it was in rev 95c44ec485b46ffb43dbdaa299f1491a500fdadf .
If your SD card is newer, you'll see in the for loop in "sd_init_card" in atmel_mci.c time out. In the 2.0 spec, you need to perform a CMD8 (SEND_IF_COND) first to see if your card is a 2.0 card. In CMD8 you tell the card the voltages you support and if you support HC cards. Once you send it the right data there, then ACMD41 will not have its BUSY bit set. That's all well and good, but additionally the CSD register is in a new format and that needs updating before any of this will work.
The best solution is to use the MMC framework, which *does* do all of these things that you suggest. It should be fairly straightforward to port the atmel_mci driver to this framework. If you see something lacking, feel free to mention it, or modify the framework. :)
Andy