Hi again,
Felipe Balbi <balbi@xxxxxxxxxx> writes:
> Thinh Nguyen <Thinh.Nguyen@xxxxxxxxxxxx> 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@xxxxxxxxxxxx>
>
> 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.
--
balbi
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