[U-Boot] i2c issues with efikamx and mainline uboot

[Konstantinos Margaritis <markos@freevec.org>]

(Disclaimer: u-boot newbie)

Hi all,

With Marek's huge help (thanks Marek!) I've tried to merge his tree [1]
that provides lcd support for the efikamx/efikasb with recent mainline
uboot. It boots, but I've hit some wall now and couldn't get passed it,
so I thought I'd ask for some expert advice, Marek suggested I mail
here and CC himself and Stefano as well.

So, I've migrated the structures to the iomux v3 coding conventions,
added some missing defines for iomuxes used, etc. I've forked the code
in github [2] and am doing all the changes there, in the hope that I can
at some point submit it back to mainline. I also want to to enable
multi-host USB support for the platform so that tftp booting will be at
last possible, but that's going to happen later, I want to be done with
LCD first.

The result boots, but in short it fails to initialise the LCD (for the
efikamx, didn't test efikasb yet). I noticed that amongst many changes,
in drivers/i2c/mxc_i2c.c, i2c_imx_bus_busy() in Marek's tree () got
sort of replaced with wait_for_sr_state(), which does the same
thing but is more generic -or so I understand, please correct me if I'm
wrong in my interpretation.

So what's the problem? Well, I2CR_MSTA (master mode) is set, but
I2SR_IBB fails to get set. In every case I get this result in the
I2SR register:

I2SR = 81 -> I2SR_ICF | I2SR_RX_NO_AK, ie. 

which according to the iMX515 Reference Manual corresponds to:

"Transfer is complete, and set by the falling edge of the ninth clock
of a byte transfer." + "A ?No acknowledge? signal was detected
at the ninth clock."

so a previous answer didn't send an acknowledge or rather the
opposite it sent a NACK. 

I'm at a loss here, attaching a boot log where I added some printfs
around. I'd appreciate any pointer as to what I'm doing wrong.

Thanks

Konstantinos

[1] git://git.denx.de/u-boot-marex.git branch: efikasb2
[2] https://github.com/markos/u-boot branch: efikamx
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