RE: [PATCH] usb: xhci-plat: Enable USB 2.0 hardware LPM support forplatform xHCs

From: Paul Zimmerman
Date: Thu Aug 22 2013 - 01:11:55 EST


> From: Julius Werner
> Sent: Wednesday, August 21, 2013 9:22 PM
>
> > You need the USB 2.0 spec errata from 2011-11 that describes the changes
> > made for BESL as well. It's in the USB2-LPM-Errata-final.pdf and
> > USB2_LinkPowerMangement_ECN[final].pdf files in this zip file:
> >
> > http://www.usb.org/developers/docs/usb_20_070113.zip
> >
> > I agree though, it's all a confusing mess for documentation on USB 2.0
> > Link PM.
>
> Thanks, I hadn't found that first one yet. Do you also have a link for
> the updated XHCI specification or a separate erratum document
> describing the PORTHLPMC register referenced in the BESL patches (they
> don't exist on DWC3, but I'm still curious)?

Just to set the record straight :)

The PORTHLPMC registers do exist on DWC3, starting with the 1.90a version
of the core or thereabouts. They only supported the HIRD flavor of LPM,
though. Only fairly recently has support for BESL been added, around
version 2.41a or so.

--
Paul

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