Re: [V4.0.0-rc3] Xhci Regression: ERROR Transfer event TRB DMA ptr not part of current TD

From: Alan Stern
Date: Tue Mar 10 2015 - 13:30:04 EST

On Tue, 10 Mar 2015, Mathias Nyman wrote:

> Yes, thank you
> Seems that It wasn't mature enough, I'll revert it.
> From your logs I can see what went wrong,
> If you still have some time, could you try out a patch (attached) and see if it solves the
> issue for you. (on top of clean 4.0-rc3). I can't reproduce it with my own USB DVB-T device


Your patch description says this:

> The endpoint might already processesed some TRBs on the endpiont ring
> before we soft reset the endpoint.
> Make sure we set the dequeue pointer to where we were befere soft reset

However, if a driver tries to issue an endpoint reset while there are
still some URBs queued, it is a bug. Host controller drivers shouldn't
have to worry about this -- xhci_endpoint_reset() should simply return
an error if the endpoint ring isn't empty.

I suppose we should check for this in the USB core. I'll write a patch
and CC: you.

Alan Stern

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