usb: dwc3: Prevent indefinite sleep in _dwc3_set_mode during suspend/resume

[Felipe Balbi <balbi@kernel.org>]

Hi,

Roger Quadros <rogerq@ti.com> writes:
>>> This is what the v3.10 databook says
>>>
>>> "When issuing an End Transfer command, software must set the CmdIOC
>>> bit (field 8) so that an Endpoint Command Complete event is generated
>>> after the transfer ends. This is necessary to synchronize the
>>> conclusion of system bus traffic before the End Transfer command is
>>> completed."
>>>
>>> with a note
>>>
>>> "If GUCTL2[Rst_actbitlater] is set, Software can poll the completion
>>> of the End Transfer command by polling the command active bit to be
>>> cleared to 0."
>>>
>>> fyi.
>>>
>>> Rst_actbitlater - "Enable clearing of the command active bit for the
>>> ENDXFER command after the command execution is completed.  This bit is
>>> valid in device mode only."
>>>
>>> So I'd prefer not to clear CMDIOC for all cases.
>>>
>>> Could we some how just tackle the dwc3_gadget_exit case like I did in
>>> this patch?
>> 
>> if you can send a version that doesn't iterate over all endpoints twice,
>> sure. We still need a comment somewhere, and I fear we may get
>> interrupts later in some cases. How would we deal with that?
>> 
>
> how about explicitly masking that interrupt? Is it possible?

I think I showed that the bit is reserved on recent dwc3 core releases
(anytyhing 2.40a+, at least).