DWC_OTG Issues

Wolfgang Denk wd at denx.de
Sun Dec 20 05:56:57 EST 2009

Dear Hunter Cobbs,

In message <1261190115.14590.5.camel at mobiLinux> you wrote:
> Hello list.  I've run into a rather odd problem.  I seem to have a
> problem with full-speed isochronous transfers across a USB2.0 Hub.  I
> believe this was observed before with the general EHCI drivers in Linux.

Which exazct kernel / driver cversions are you talking about?

> In the latest branch of the kernel, the EHCI driver has some "Enhanced
> Transaction Translation" scheduling.  This would be great for me to use
> as it seems to directly address the issues I've seen.  However, I'm not
> really sure on how to proceed because the DWC_OTG driver is not GPL code

Oops? if that wa the case you could not use (and distribute) this code
in a Linux context at all.

> while the EHCI code I'd like to use is.  Therefore, I don't believe that
> I can port the Enhanced Transaction Translation routine into the DWC_OTG
> driver without violating both the GPL and Synopsis's own driver.

What makes you think so?

The Synopsis dwc_otg driver license does not seem to be  in  conflict
to  the  GPL,  if  you  ask  me (but then, I am not a layer). When we
worked on this, we were assured that the use of this driver source in
the context of GPLed software like the Linux kernel (or  U-Boot)  was
not considered an issue by Synopsis.

> Does anyone have a suggestion on how to proceed?

We have been doing some work on the DWC drivers in the past, fixing a
number of issues. [We never  attempted  to  psuh  any  of  this  into
mainline  as  the  Synopsis  drivers  are  -  in  our  opinion  - not
avcceptable for mainline but require more  or  less  a  rewrite  from
scratch. But you can find all this stuff in our linux-2.6-denx repo.]

I recommend you give a try to our latest stable branch.

Best regards,

Wolfgang Denk

DENX Software Engineering GmbH,     MD: Wolfgang Denk & Detlev Zundel
HRB 165235 Munich, Office: Kirchenstr.5, D-82194 Groebenzell, Germany
Phone: (+49)-8142-66989-10 Fax: (+49)-8142-66989-80 Email: wd at denx.de
What is research but a blind date with knowledge?      -- Will Harvey

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