[Linux-stm32] [PATCH V4 21/22] ARM: dts: stm32: Add bindings for USB on AV96

[Marek Vasut]

On 4/10/20 1:34 PM, Manivannan Sadhasivam wrote:
> On Fri, Apr 10, 2020 at 11:16:53AM +0200, Marek Vasut wrote:
>> On 4/10/20 11:08 AM, Manivannan Sadhasivam wrote:
>>> Hi,
>>
>> Hi,
>>
>>> On Tue, Apr 07, 2020 at 08:37:50PM +0200, Marek Vasut wrote:
>>>> On 4/6/20 1:08 PM, Marek Vasut wrote:
>>>>> On 4/6/20 9:22 AM, Manivannan Sadhasivam wrote:
>>>>>> On Wed, Apr 01, 2020 at 03:22:36PM +0200, Marek Vasut wrote:
>>>>>>> Fill in the bindings for USB host and gadget on AV96.
>>>>>>>
>>>>>>> Signed-off-by: Marek Vasut <marex at denx.de>
>>>>>>
>>>>>> I can't get the USB B-Micro OTG port to work with this patch. Do I need to
>>>>>> enable any configs other than PHY and USB DWC2 drivers?
>>>>>
>>>>> Only the DWC2 GADGET (and possibly host, for dual-role) and some gadget
>>>>> implementation (e.g. gadget zero).
>>>>
>>>> I think I see what doesn't work for you.
>>>>
>>>> It seems the following works on next:
>>>> power on -> plug in USB stick (or any other USB device) -> unplug ->
>>>> plug in usb host (e.g. PC)
>>>>
>>>> But this does not:
>>>> power on -> plug in usb host (e.g. PC)
>>>>  - the PC is not detected
>>>>
>>>
>>> Both doesn't work. I have the rndis gadget configured in userspace but plugging
>>> in the micro-b cable doesn't do anything.
>>>
>>>> Did that ^ ever work for you before ? I suspect this is a bug in the
>>>> DWC2 driver. The OTG operation there is known to be flaky at best.
>>>
>>> Not on this board. I don't recall what happended with vendor image. But I do
>>> have another STM32MP1 based 96Board (which will be submitted soon), there I can
>>> get OTG port working.
>>>
>>> But in that board a BG96 modem is connected to USB2 port on the board itself
>>> which gets enumerated during probe.
>>
>> But it's not configured as OTG on this other board, right ?
> 
> It is configured as a OTG port. But that board has a different issue which
> resets the board when we connect any OTG cable to act as a host. That's not
> related to DWC2 or this issue btw.

Do I misunderstand the part where you claim there is a modem connected
to the DWC2 ? That would mean it's in Host mode, no ?

> Anyway, I can't get OTG (device/host) to work on both old and new boards.

Do you have 588-200 now too ?

I think there is some fix in current linux-next which partly fixes the
DWC2 role switching, so rebase this patchset on current linux-next and
see what happens. But it's still not perfect. I also think that ST
managed to side-step this issue by using the STUSB1600 chip, but I might
be wrong.