MMC msdos fs corrupt when files copied in shell

[Gene Smith]

Starting with a cleanly formatted fat16 MMC containing some random txt 
files, if I try to copy them to new files using the shell cp command, 
they seem to work but when put on a pc (linux or windows) the new files 
are always corrupted and there are additional files present with random 
names that were never copied.

Also, when I first mount the cleanly formatted fat16 MMC (or fat32) and 
do ls in the shell I see a couple of random spurious files listed. This 
is before I do any copies. If I try to ls those files, the shell says 
they don't exist.

Also if I unmount and re-mount the MMC with the shell I see the copied 
new files corrupted when cat'ing in the shell. I have varied my MMC 
clock speed from 400Khz to 25Mhz with the same result (just copies 
faster at higher clock rate). I intend to run at 12.5Mhz (below the max 
20Mhz MMC speed).

I see no errors occurring with SYSLOG (DEBUG is defined in 
spi-sd-card.c). So not sure what the problem is. Can others copy files 
around on a SD/MMC with the shell and obtain good results?

I still need to try the mount and copies with c library calls in some 
test code independent of the shell.

-gene