I created to documents some issues with my alternate kernel patch for Compulab cm-x255 and cm-x270w boards located at

If you want to help fix or explain something, please contact me at

Please note that the this page is not complete.

[cm-x255] USB Gadget (usb slave)
I got linking errors when building usb gadget support into the kernel:
eth_unbind' referenced in section `.init.text' of drivers/built-in.o: defined
in discarded section `.exit.text' of drivers/built-in.o
I found a workaround but I dont understand why it was needed and why it works:

Remove the __exit from the eth_unbind function (ether.c:2137) and dont use __exit_p in struct usb_gadget_driver (ether.c:2552). A similar workaround may be needed for other gadget drivers.

[cm-x270] USB Gadget (usb slave)
PXA270 usb slave support is based on the 2.6 kernel CVS and this patch.

I had a little trouble getting this to work. All gadget drivers I tried failed to autoconfigure. I noticed in the patch above that all gadget drivers were patched to call gadget->ops->ep_alloc instead of using usb_ep_autoconfig. Instead of doing the same thing which would not work on the cm-x255, I added the following two lines to epautoconf.c, which seems to work fine:
--- ../../../../linux-  2006-05-24 21:50:17.000000000 -0400
+++ epautoconf.c        2006-06-21 11:27:05.000000000 -0400
@@ -238,6 +239,9 @@
@@ -238,6 +239,9 @@
        type = desc->bmAttributes > USB_ENDPOINT_XFERTYPE_MASK;
+       if (gadget_is_pxa27x (gadget))
+               return gadget->ops->ep_alloc(gadget, desc, epconfig, numconfigs);
        /* First, apply chip-specific "best usage" knowledge.
         * This might make a good usb_gadget_ops hook ...

[cm-x2xx] DM9000 Ethernet
I used the dm9000 driver from a vanilla kernel. Added platform data in cm-x270.c and cm-x255.c to make it work. However, there is a small bug: The MAC address is NULL! In Compulab's version of the driver, they read the MAC address differently. For the moment, I added calls to machine_is_cm_x270() and machine_is_cm_x255() and use the Compulab way to get the MAC address, which works.

[cm-x2xx] IT8152 PCI Controller
Those boards use the it8152 pci controller (I think there are other peripherals integrated in this chip but I cannot find any documentation and ITE does not respond to my mails). Compulab's patch touches/creates the following files:
For the cm-x255, I combined IT8152-pci.c and IT8152-pcistruct.c into one file named it8152.c. I also renamed some interrupt names in include/asm-arm/arch-pxa/irqs.h. All this stuff needs to be reworked to be cleaner.

I have not yet started working on the cm-x270 PCI support.

[cm-x2xx] UCB1400 (For touchscren controller function)
The UCB1400 is an AC97 codec with an integrated 4 wire touchscreen controller used on CM-X255 and CM-X270 when they are built with touchscreen support.

The most recent patches I could find for this chip were posted by Nicolas Pitre on the linux-arm-kernel mailing list on Wed Mar 30 2005:
Some modifications were necessary since those patches were originally for 2.6.12. Here is how I applied them on 2.6.17-rc6:
For your convenience, here are the patches updated for 2.6.17-rc6:

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