Re: [RFC/PATCH v2] usb: host: xhci: issue 'Reset Endpoint' for !CONTROL EPs from finish_td()

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Hi,

On Fri, Nov 14, 2014 at 09:04:16AM -0600, Felipe Balbi wrote:
> On Fri, Nov 14, 2014 at 10:39:15AM +0200, Mathias Nyman wrote:
> > On 13.11.2014 20:46, Felipe Balbi wrote:
> > > On Thu, Nov 13, 2014 at 12:31:28PM -0600, Felipe Balbi wrote:
> > >> Hi,
> > >>
> > >> (your mailing is un-wrapping emails, I always end up with pretty long
> > >> lines and have to rewrap them)
> > >>
> > >> On Thu, Nov 13, 2014 at 07:58:28PM +0200, Mathias Nyman wrote:
> > >>>> The algorithm described in the DVB tuner bug is clearly wrong, since
> > >>>> it doesn't move the dequeue pointer until usb_clear_halt() is
> > >>>> called, which is far too late.  The right approach is to fix up the
> > >>>> dequeue pointer before giving back the URB (so there's no need to
> > >>>> save a "stopped TD" value).  Otherwise there will be TDs in the
> > >>>> endpoint ring containing stale DMA pointers to buffers that have
> > >>>> already been unmapped.
> > >>>
> > >>> Thats right, I cleaned up the patch and removed resetting the endpoint
> > >>> from the .endpoint_reset() callback which was called as a result of
> > >>> usb_clear_halt(). Now we queue a reset endpoint and set dequeue
> > >>> pointer before giving back the URB.
> > >>>
> > >>> I still set a "stopped td" value, but could as well just pass it as
> > >>> function parameter.  Actually I'll do that in later cleanup patch.
> > >>>
> > >>> Latest version of the patch is now in my tree in a reset-rework-v2
> > >>> branch, with fixes comments and removed The brach includes the other
> > >>> dorbell ringing patch as well.  both are on top of 3.18-rc4.
> > >>>
> > >>> I still need to test it before sending it further, the tree is here:
> > >>>
> > >>> git://git.kernel.org/pub/scm/linux/kernel/git/mnyman/xhci.git  reset-rework-v2
> > >>
> > >> I'll test this one.
> > > 
> > > for both commits on that branch, you can add my:
> > > 
> > > Tested-by: Felipe Balbi <balbi@xxxxxx>
> > > 
> > > But please also add proper fixes and Cc: stable, so older kernels can
> > > use those.
> > > 
> > 
> > Thanks a lot for testing again.
> > 
> > I'll CC stable and add your tested-by, but I still don't know exactly
> > which commit it Fixes. This might have been there since the early days
> > of xhci.
> 
> git blame usually helps. Just look for code which was differentiating
> COMP_STALL and treating it differently. I know that at least v3.14 has
> the problem.

Here you go:

Fixes: bcef3fd (USB: xhci: Handle errors that cause endpoint halts.)
Cc: <stable@xxxxxxxxxxxxxxx> # v2.6.33+

Please make sure to send these patches ASAP otherwise they will not hit
v3.18-final, it's getting pretty late.

cheers

-- 
balbi

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