Patch to make BBB properly boot from eMMC every time

[Ian Lepore]

On Tue, 2014-05-13 at 10:17 -0400, Winston Smith wrote:
> On Tue, May 13, 2014 at 9:30 AM, Ian Lepore <ian at freebsd.org> wrote:
> > Confused about the cause of the results, yes.  I think the printf I had
> > you add to help me figure out the problem just changed the timing of the
> > retry to make it work on the second try, but I have no idea why.
> >
> > Does anybody else with a BBB see the device randomly boot up as 1 or 4
> > or 8 bits, changing from one boot to the next?  The bits are reported in
> > the mmcsd0 line:
> >
> > mmcsd0: 8GB <SDHC SA08G 0.4 SN 2630755555 MFG 10/2009 by 2 TM> at mmc0
> > 50.0MHz/4bit/65535-block
> >
> > That's from a wandboard, but a BBB eMMC should always be 8 bits.
> 
> BBB rev A6A shows 8-bits (for the eMMC):
> 
> mmcsd1: 2GB <MMC MMC02G 3.10 SN 244024444 MFG 08/1997 by 254 0x004e>
> at mmc1 48.0MHz/8bit/65535-block
> 
> 
> But shows 4-bits for the SD card:
> 
> mmcsd0: 4GB <SDHC SA04G 0.4 SN 2617266666 MFG 05/2010 by 2 TM> at mmc0
> 48.0MHz/4bit/65535-block

4 bits is normal for an sdcard, that's all the data lines an sdcard has.
An emmc card/chip can have 1, 4, or 8.

Does your emmc come up as 8-bit reliably every time?

-- Ian