USB On PCM043?

Sascha Hauer s.hauer at
Thu Jul 19 12:11:39 EDT 2012

On Thu, Jul 19, 2012 at 03:37:47PM +0000, Jerry Kirk wrote:
> We have been attempting to get USB Host mode working under Barebox(2012-07-0) on 
> a PCM043 platform (i.mx35), but we are having a bit of trouble.
> We have  merged the CONFIG_USB specific code for "imx35_devices_init" and 
> "imx35_usb_init" from the Eukrea platform into pcm043.c, added the 
> pad definitions (as per the main kernel pcm043.c file), added the "tmp |= 0x3 << 
> CCM_CGR2_USB_SHIFT" to enable the USB clock to "pcm043_core_setup", built 
> everything with the "usb" command enabled, and then loaded the new Barebox image 
> into our pcm043 board. We have USB_EHCI and USB_STORAGE enabled in the Barebox 
> config.
> If I execute the "usb" command then it returns that it has found 1 EHCI 
> controller. If I plug in any device, the only one it has EVER detected has been 
> a USB mouse. It will be detected most of the time following a reset and after 
> unplugging/replugging the mouse -- but will never be detected again after this 
> unless I do a reset/replug operation (and never on a "usb -f" forced redetect).
> Basically, our goal is to get USB flash drives working for use as a means of 
> upgrading our Linux kernel in the field -- but right now it won't even EVER 
> recognize a USB flash drive when it is plugged into the unit. We also know it is 
> not a hardware problem as all USB devices work just fine once the full kernel 
> finishes booting.
> From what we have read, it looks like the Eukrea platform had USB working in it, 
> and we have attempted to use it as a guide, but we still aren't having any luck.
> Does anyone know of any steps we might be missing? Or of anyone who has gotten 
> USB host mode working on a pcm043 under Barebox before?
> I think we are close, but something (obviously) still isn't right.

Could it be that the USB clock operates at the wrong rate? I think it
should be 60MHz.


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