dts,i2c,pcf8574 on Xilinx XUP

[ST]

Hi
> (BTW your full name in the mail header would be appreciated)
If the internet would be forgetting more...
 
> > [2797861247.810511] i2c /dev entries driver
> > [2797861247.817952] Device Tree Probing 'i2c'
> > [2797861247.830658]  #0 at 0x81600000 mapped to 0xD10C0000, irq=20
> > [2797861247.838743] pcf857x: probe of 0-0020 failed with error -22
> 
> Doesn't look good here. Do you have the latest version of the driver?
> (CCing i2c)
Mh, i just saw that the i2c-xii.h file is now in 2.6.34. I copied them to my 
2.6.32-xlnx tree. So i think this is the most recent driver (albeit not the most
recent kernel 2.6.32 due to the fact that vanilla doesn't boot on my machine).

> > 		xps_iic_0: i2c at 81600000 {
> > 			compatible = "xlnx,xps-iic-2.00.a";
> > 			interrupt-parent = <&xps_intc_0>;
> > 			interrupts = < 1 2 >;
> > 			reg = < 0x81600000 0x10000 >;
> > 			xlnx,clk-freq = <0x17d7840>;
> > 			xlnx,family = "virtex2p";
> > 			xlnx,gpo-width = <0x1>;
> > 			xlnx,iic-freq = <0x186a0>;
> > 			xlnx,scl-inertial-delay = <0x0>;
> > 			xlnx,sda-inertial-delay = <0x0>;
> > 			xlnx,ten-bit-adr = <0x0>;
> 
> Have you checked the values? There is surely
> 
>                         #address-cells = <1>;
>                         #size-cells = <0>;
> 
> missing here, but that shouldn't cause your problems IMHO. I probably can't
> help any further, never used Xilinx so far (you have the newest version of
>  the dts-generator?).
The messages come from dts-v1.1.0 included in ptxdist-2010.03.0. The warnings are gone
after inserting your suggested lines into the dts file. Thanks for that hint! However the error 
that no PCF devices are found on the bus still persists. However there is absolutly no i2c traffic 
on the i2c pins while it probes for the pcf device, so there clearly is s.t. amiss.
Reconfiguring the pins to gpio pins works as expected, so the raw hardware (not the "soft" hw)
is working. 

Possible causes i see:
* i did an error when backporting these changes. But since there was only a kconfig entry besides 
  adding the c and header file, this would be still possible.
* I did some error in building the hardware.
* The i2c-xii driver is not working on powerpc hardware (only µblaze).
If anybody has some suggestions or knows that the i2c-xii driver
works on powerpc would be really happy to know.

Concerning the xilinx xup board, i am kind of frustrated: There is no support for newer 
design tools than 10.1 [1]. Then there had been a regression in the systhesis tools which 
couldn't handle 512 Mb memory sticks anymore (works with 256Mb). Then
the git tree is only sometimes online? There is no i2c (compiling) driver for their stuff 
which is then added by Intel? So Wolfram you can probably consider yourself lucky ;-).

Thanks
ST

[1] http://www.digilentinc.com/Products/Detail.cfm?NavPath=2,400,794&Prod=XUPV2P