>> The board is a Compulab CM-X270L (PXA270). This board has USB master as >> well as a slave port. It's currently running a patched 2.6.16 kernel >> (the patch is from Compulab). It runs Compulab's Debian distribution >> - "Debian GNU/Linux 3.1". > > Wow, that's old and out of date, and very obsolete. yes...I realized that! :) > >> We need to use the board as a USB slave to a machine which has a USB >> master (root hub). This machine runs a proprietary OS and we do not >> have access to it's source code and/or any other means to access it's >> internals. > > What OS is it? I think it's some variant of uCos...not sure though... > >> This proprietary OS supports the following USB classes: >> >> I plan to do the following: >> >> 1) CDC-ACM: Compile the USB gadget serial driver as a LKM for the board. >> If the module loads successfully, connecting the slave port to the >> host should make it (the slave), enumerate successfully as an ACM >> device. > > Did that work? No, since I can't reflash the board with a newer kernel I'm forced to use the existing pxa27x_udc module (built for 2.6.16 with the compulab patch applied). When I loaded the serial module (g_serial), I get the following error: gs_module_init: cannot register gadget driver, ret=-16 I also got this once inserting the module: gs_bind: cannot autoconfigure on pxa27x_udc gs_module_init: cannot register gadget driver, ret=-19 > >> 2) CDC-ECM: This one's a bit tricky! I understand that the ethernet is >> implemented in drivers/usb/gadget/ether.c. But, since the host side >> driver is written to work with a particular chipset, will it work >> "AS IS" with the ethernet gadget driver? > > It should. > >> Also, in case it doesn't work, can I tweak the gadget driver to make >> it work/enumerate correctly with the host? Basically I'll be "faking" >> the chip in s/w. > > Sure, you could. > >> Also, how can I verify that the kernel has recognized the USB slave >> device? > > Look at the log messages? Ok. I got this: # dmesg | grep -i udc pxa27x_udc: version 08-Feb-2007 UDC Configuration Passed > >> During kernel configuration, we can choose gadget support as a module. >> Is there a separate module that needs to be present for gadget support or >> will individual gadget drivers themselves provide this functionality? > > Your gadget controller needs to be loaded as well. I just found the config file for the running kernel (under /proc/config.gz) and it shows that the udc's built-in into the kernel (unfortunately not as a module which i can change). > >> The following link states that the USB device functionality is not >> supported >> in 2.6.16 kernels: >> >> http://www.compulab.co.il/mediawiki/index.php5?title=Linux_Kernel_for_CM-X270#USB_device >> >> But if I get the patches mentioned in the link and compile them as >> modules, >> then can I enable the USB device functionality? > > Probably upgrade to a newer kernel version. YOu do realize how old > 2.6.16 is, right? Yes, I plan to do that as soon as I figure how to re-flash the board. > > Contact your manufacturer? Can you suggest any good boards for USB peripheral driver development? I need something thats well-supported under linux. Is the NetChip 2280 a good option? I've heard that the PXA27x's UDC has some issues (read it in some thread on LKML)...also I don't want to cross-compile a module if it can be avoided! :) If i use a netchip card, then I can compile my modules natively (x86) and test things out...right? > > good luck, Thanks, -mandeep > > greg k-h > -- To unsubscribe from this list: send the line "unsubscribe linux-usb" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
