[MX25][MMC] mmc esdhc failure in 3.3

[joancarles]

> Anybody with more insights? Why is the interval between two CMD24
> more or less in the range of 6ms and the CMD13 follows in varying
> intervals between 1ms to 4ms? What's keeping the driver from bursting
> CMD24 and successive CMD13 requests?

A 4*128KB dd run shows the following patterns of latency between 
various CMDs issued:

http://i43.tinypic.com/2bcmsw.png

The latency distribution is plotted here:

http://i41.tinypic.com/9gvbqo.png

bin limits	freq count	pct
<0ms	0	0.0%
<1ms	922	43.6%
<6ms	491	23.2%
<10ms	411	19.4%
<20ms	113	5.3%
<100ms	163	7.7%
<300ms	9	0.4%
<1000ms	7	0.3%

It took 25 seconds to write 4*128KB to the SD-card using the current 
drivers. More than 50% of the CMD requests issued take more than 1ms 
from issuing to response between the host and the card. Anybody else 
with this issue on the i.MX25? How can I pinpoint this down to the 
culprits in the kernel source?

Regards
-- 
Joan C. Abelaira