Re: [PATCH 2/3] usb: dwc3: gadget: Fix early exit in set/clear ep halt

[Thinh Nguyen <Thinh.Nguyen@synopsys.com>]

Hi Felipe,

On 4/11/2017 11:03 PM, Felipe Balbi wrote:
> 
> Hi,
> 
> Thinh Nguyen <Thinh.Nguyen@synopsys.com> writes:
>>>>> Felipe Balbi <balbi@kernel.org> writes:
>>>>>> Thinh Nguyen <Thinh.Nguyen@synopsys.com> writes:
>>>>>>> This patch fixes a commit that causes a hang from device waiting for
>>>>>>> data with the wrong sequence number. The commit ffb80fc672c3 ("usb:
>>>>>>> dwc3: gadget: skip Set/Clear Halt when invalid") adds a check to return
>>>>>>> early depending on DWC3_EP_STALL is set or not, prevent sending the ep
>>>>>>> halt command to HW endpoint to do CLEAR_FEATURE(ENDPOINT_HALT) request.
>>>>>>> This was to workaround the issue for macOS where the device hangs from
>>>>>>> sending DWC3 clear stall command.
>>>>>>>
>>>>>>> In USB 3.1 spec, 9.4.5, CLEAR_FEATURE(ENDPOINT_HALT) request always
>>>>>>> results in the data sequence being reinitialized to zero regardless
>>>>>>> whether the endpoint has been halted or not. Some device class depends
>>>>>>> on this feature for its protocol. For instance, in mass storage class,
>>>>>>> there is MSC reset protocol that does CLEAR_FEATURE(ENDPOINT_HALT) on
>>>>>>> bulk endpoints. This protocol reinitializes the data sequence and
>>>>>>> ensures that whatever pending data requested from previous CBW will be
>>>>>>> reset. Otherwise this will cause a hang as the device can wait for the
>>>>>>> data with the wrong sequence number from the previous CBW. We found this
>>>>>>> failure in USB CV: MSC Error Recovery Test with f_mass_storage.
>>>>>>>
>>>>>>> This patch fixes this issue by checking to see whether the set/halt ep
>>>>>>> call is a protocol call before early exit to make sure that set/clear
>>>>>>> halt endpoint command can go through if it is a device class protocol.
>>>>>>>
>>>>>>> Fixes: ffb80fc672c3 ("usb: dwc3: gadget: skip Set/Clear Halt when invalid")
>>>>>>> Signed-off-by: Thinh Nguyen <thinhn@synopsys.com>
>>>>>>
>>>>>> this will regress the macOS case I wrote that commit for. We need to
>>>>>
>>>>> no wait, it won't regress macOS, but we're still left with the problem
>>>>> of host and peripheral being able to get DataToggle/SeqN out of sync.
>>>>>
>>>>
>>>> This patch is for the regression we have. Can you provide more
>>>> information for the macOS? I'm not sure if this is the case for macOS,
>>>
>>> I need to find a way to reproduce it again first. When I first
>>> reproduced it was with dwc3 running adb and connecting it to a macOS
>>> machine.
>>>
>>>> but maybe there is still pending transfer when it tries to send the
>>>> request? (There shouldn't be any before issuing ClearStall command). Do
>>>
>>> this could be, I don't remember if I checked this or not :-)
>>>
>>> Really, the best way here, IMHO, would be to re-verify what's going on
>>> with macOS and revert my orignal patch since it's, rather clearly,
>>> wrong.
>>>
>>
>> Sure. Are you going to make a revert patch or I am?
> 
> Well, after we really know what's going on with macOS and have a better
> fix, then who makes the revert is less important as long as problems get
> sorted out :-) Either way is fine for me.
> 

Do you have any update on this issue?

BR,
Thinh