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

[Benoît Thébaudeau]

Dear Marek Vasut,

On Tuesday, November 19, 2013 4:37:00 PM, Marek Vasut wrote:
> Dear Konstantinos Margaritis,
> 
> > (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.
> 
> Honestly, I have a feeling the MX51 I2C controller might be broken. Isn't
> there
> maybe something in the ERRATA for MX51 (I know it's HUGE) ?

I use the i.MX515, and the I²C worked fine at some point in mainline U-Boot. If
it does not work for you now, it's either because of a software regression, or
because of some board-specific issue, e.g. pads. SION may have to be set for
I²C.

Best regards,
Benoît