[MX25][MMC] mmc esdhc failure in 3.3

[joancarles]

Hi

>> Interesting question is now why it worked on your older kernel? The 
>> code
>> around BROKEN_TIMEOUT is there for much longer, I'd think.
>>
> not in fact it seems to have been broken from a long time and I think
> I'm responsible of that in 37865fe91582582a6f6c00652f6a2b1ff71f8a78
> "mmc: sdhci-esdhc-imx: fix timeout on i.MX's sdhc"
> because unlike the i.MX35 it seems that the i.MX25 manages to read
> properly the partition table even without the timeout quirk and it
> seems that I didn't do more extensive tests for this patch.

Might be unrelated, however I have been keeping my eyes on the fix of 
ENGcm07207 quirk introduced with 16a790bcc. According to the 
IMX25CE.pdf, to abort data transfers on the AHB, software can reset the 
eSDHC by writing 1 to SYSCTL[24] (RSTA), which currently is not done 
with SDHCI_QUIRK_NO_MULTIBLOCK. It sets the max_blk_count to 1 instead 
of 65535. Not sure if this is also limiting the speed.

I have tried putting the SD card into an ALL-in-One reader via USB and 
I get 6MB/s read and 15MB/s write performance. Since I didn't know the 
exact class of the card, this reassures me that there is nothing 
substantially wrong with the card per se.

So, how can we find a solution to this speed issue? Also, do you plan 
on submitting your patch to revert the timeout quirk for MX25?

Cheers
-- 
Joan C. Abelaira