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

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On 14.11.2014 17:49, Felipe Balbi wrote:
> 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.
> 

Amazing, was still struggling trying to figure out which one it was.
It goes back a long way, I'll send the patches right away.

I btw now got a device I should be able to load gzero on, once I figure
out how to flash it.

Thanks again

-Mathias
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