Re: [Libusbx-devel] usbdevfs: BULK_CONTINUATION flag does not work with XHCI controller

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On Fri, 25 May 2012, Hans de Goede wrote:

> > Judging by your description, there is a bug either in xhci-hcd or in
> > your xHCI hardware.  What does "lspci -vv" show for the controller?
> 
> 01:00.0 USB Controller: NEC Corporation uPD720200 USB 3.0 Host Controller (rev 04) (prog-if 30 [XHCI])
>          Control: I/O- Mem+ BusMaster+ SpecCycle- MemWINV- VGASnoop- ParErr- Stepping- SERR- FastB2B- DisINTx+
>          Status: Cap+ 66MHz- UDF- FastB2B- ParErr- DEVSEL=fast >TAbort- <TAbort- <MAbort- >SERR- <PERR- INTx-
>          Latency: 0, Cache Line Size: 64 bytes
>          Interrupt: pin A routed to IRQ 16
>          Region 0: Memory at fe600000 (64-bit, non-prefetchable) [size=8K]
>          Capabilities: <access denied>
>          Kernel driver in use: xhci_hcd

As far as I know, the NEC controllers have been very reliable.

> But I don't believe this is hardware specific, I started investigating this
> after a bug report from a user of my USB redirection code, that user
> was seeing this with a thinkpad W510. I'll ask an lsusb -vv from him too,
> just in case that model has the exact same hardware.
> 
> I'm thinking that maybe the issue is that the EREMOTEIO error gets generated
> by the driver based on the SHORT_NOT_OK flag (or so I believe), not the hc
> itself, could it be that the code doing that does not halt the ep, or halts
> it too late?

Well, the EREMOTEIO error is _supposed_ to be generated by the 
controller.  That is, the hardware is supposed to recognize it as an 
exceptional case and stop the endpoint queue.

Sarah knows the answers; she's the xhci-hcd maintainer.  Anything I 
said about it would just be speculation.

Alan Stern

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