[Bug?] Control Transfers in xHCI

[Chagin Dmitry]

On Thu, Jan 29, 2015 at 04:04:03PM +0100, Hans Petter Selasky wrote:
> On 01/29/15 13:25, Kohji Okuno wrote:
> > Hi HPS,
> >
> > I found a bug in xHCI device driver.
> >
> > Acording to extensible-host-controler-interface-usb-xhci.pdf:"3.2.9
> > Control Transfers"...
> >
> > A Data Stage TD consists of a Data Stage TRB followed by zero or more
> > Normal TRBs. If the data is not physically contiguous, Normal TRBs may
> > be chained to the Data Stage TRB.
> >
> >
> > But, in the current imprementation, when two or more TRBs are needed,
> > the device driver set XHCI_TRB_TYPE_DATA_STAGE to all TRBs.
> > This is the violation of the spec.
> >
> > In my minor xHCI, I encountered strange bubble error in a control
> > transfer. After I changed as the following, I succeeded its control
> > transfer.
> >
> > Would you check the following (****)?
> >
> 
> Hi Kohji,
> 
> You are correct there is a bug, but your patch is not correct.
> 
> In FreeBSD we allow SETUP and DATA stages to be done as separate jobs. 
> That means at the entry of creating a new DATA chain, we need to check 
> if it is there first DATA packet or not.
> 
> Can you test the attached patch and see if it works for you?
> 
patch is lost somewhere, Hans.
-- 
Have fun!
chd