[U-Boot] at91sam9g45ekes SDHC/MMC

[Albin Tonnerre]

On Fri, 23 Apr 2010 16:58 -0500, Andy Fleming wrote :
> On Thu, Apr 22, 2010 at 7:51 PM, Rob Emanuele <rob at 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.  :)

I did port the atmel_mci driver to the MMC framework and posted the results on
this mailing list a few months back. However, some people apparently experienced
issues I have never been able to reproduce, and got few review.
I recently adapted the AT91 SD/MMC support patch and the atmel_mci port to use
the new C structures access, I'll repost it in a couple days in case anyone's
interested.

Cheers,
-- 
Albin Tonnerre, Free Electrons
Kernel, drivers and embedded Linux development,
consulting, training and support.
http://free-electrons.com