Re: [PATCH v3] usb: dwc3: core: Do core softreset when switch mode

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

Ferry Toth wrote:
> Hi
> 
> Op 16-04-2021 om 00:23 schreef Thinh Nguyen:
>> Thinh Nguyen wrote:
>>> From: Yu Chen <chenyu56@huawei.com>
>>> From: John Stultz <john.stultz@linaro.org>
>>>
>>> According to the programming guide, to switch mode for DRD controller,
>>> the driver needs to do the following.
>>>
>>> To switch from device to host:
>>> 1. Reset controller with GCTL.CoreSoftReset
>>> 2. Set GCTL.PrtCapDir(host mode)
>>> 3. Reset the host with USBCMD.HCRESET
>>> 4. Then follow up with the initializing host registers sequence
>>>
>>> To switch from host to device:
>>> 1. Reset controller with GCTL.CoreSoftReset
>>> 2. Set GCTL.PrtCapDir(device mode)
>>> 3. Reset the device with DCTL.CSftRst
>>> 4. Then follow up with the initializing registers sequence
>>>
>>> Currently we're missing step 1) to do GCTL.CoreSoftReset and step 3) of
>>> switching from host to device. John Stult reported a lockup issue seen
>>> with HiKey960 platform without these steps[1]. Similar issue is observed
>>> with Ferry's testing platform[2].
>>>
>>> So, apply the required steps along with some fixes to Yu Chen's and John
>>> Stultz's version. The main fixes to their versions are the missing wait
>>> for clocks synchronization before clearing GCTL.CoreSoftReset and only
>>> apply DCTL.CSftRst when switching from host to device.
>>>
>>> [1]
>>> https://urldefense.com/v3/__https://lore.kernel.org/linux-usb/20210108015115.27920-1-john.stultz@linaro.org/__;!!A4F2R9G_pg!PW9Jbs4wv4a_zKGgZHN0FYrIpfecPX0Ouq9V3d16Yz-9-GSHqZWsfBAF-WkeqLhzN4i3$
>>>
>>> [2]
>>> https://urldefense.com/v3/__https://lore.kernel.org/linux-usb/0ba7a6ba-e6a7-9cd4-0695-64fc927e01f1@gmail.com/__;!!A4F2R9G_pg!PW9Jbs4wv4a_zKGgZHN0FYrIpfecPX0Ouq9V3d16Yz-9-GSHqZWsfBAF-WkeqGeZStt4$
>>>
>>>
>>> Cc: Andy Shevchenko <andy.shevchenko@gmail.com>
>>> Cc: Ferry Toth <fntoth@gmail.com>
>>> Cc: Wesley Cheng <wcheng@codeaurora.org>
>>> Cc: <stable@vger.kernel.org>
>>> Fixes: 41ce1456e1db ("usb: dwc3: core: make dwc3_set_mode() work
>>> properly")
>>> Signed-off-by: Yu Chen <chenyu56@huawei.com>
>>> Signed-off-by: John Stultz <john.stultz@linaro.org>
>>> Signed-off-by: Thinh Nguyen <Thinh.Nguyen@synopsys.com>
>>> ---
>>> Changes in v3:
>>> - Check if the desired mode is OTG, then keep the old flow
>>> - Remove condition for OTG support only since the device can still be
>>>    configured DRD host/device mode only
>>> - Remove redundant hw_mode check since __dwc3_set_mode() only applies
>>> when
>>>    hw_mode is DRD
>>> Changes in v2:
>>> - Initialize mutex per device and not as global mutex.
>>> - Add additional checks for DRD only mode
>>>
>>>   drivers/usb/dwc3/core.c | 27 +++++++++++++++++++++++++++
>>>   drivers/usb/dwc3/core.h |  5 +++++
>>>   2 files changed, 32 insertions(+)
>>>
>> Hi John,
>>
>> If possible, can you run a test with this version on your platform?
>>
>> Thanks,
>> Thinh
>>
> I tested this on edison-arduino with this patch on top of usb-next
> (5.12-rc7 + "increase BESL baseline to 6" to prevent throttling").
> 
> On this platform there is a physical switch to switch roles. With this
> patch I find:
> 
> - switch to host mode always works fine
> 
> - switch to gadget mode I need to flip the switch 3x (gadget-host-gadget).
> 
> An error message appears on the gadget side "dwc3 dwc3.0.auto: timed out
> waiting for SETUP phase" appears, but then the device connects to my PC,
> no throttling.
> 
> - alternatively I can switch to gadget 1x and then unplug/replug the cable.
> 
> No error message and connects fine.
> 
> - if I flip the switch only once, on the PC side I get:
> 
>   kernel: usb 1-5: new high-speed USB device number 18 using xhci_hcd
>   kernel: usb 1-5: New USB device found, idVendor=1d6b,
>   idProduct=0104, bcdDevice= 1.00 kernel: usb 1-5: New USB device
>   strings: Mfr=1, Product=2, SerialNumber=3 kernel: usb 1-5: Product:
>   USBArmory Gadget kernel: usb 1-5: Manufacturer: USBArmory kernel:
>   usb 1-5: SerialNumber: 0123456789abcdef kernel: usb 1-5: can't set
>   config #1, error -110

The device failed at set_configuration() request and timed out. It
probably timed out from the status stage looking at the device err print.

> 
> Then if I wait long enough on the gadget side I get:
> 
>   root@yuna:~# ifconfig
> 
>   usb0: flags=-28605<UP,BROADCAST,RUNNING,MULTICAST,DYNAMIC> mtu 1500
>   inet 169.254.119.239 netmask 255.255.0.0 broadcast 169.254.255.255
>   inet6 fe80::a8bb:ccff:fedd:eef1 prefixlen 64 scopeid 0x20<link>
>   ether aa:bb:cc:dd:ee:f1 txqueuelen 1000 (Ethernet) RX packets 490424
>   bytes 735146578 (701.0 MiB) RX errors 0 dropped 191 overruns 0 frame
>   0 TX packets 35279 bytes 2532746 (2.4 MiB) TX errors 0 dropped 0
>   overruns 0 carrier 0 collisions 0
> 
> (correct would be: inet 10.42.0.221 netmask 255.255.255.0 broadcast
> 10.42.0.255)
> 
> So much improved now, but it seems I am still missing something on plug.
> 

That's great! We can look at it further. Can you capture the tracepoints
of the issue. Also, can you try with mass_storage gadget to see if the
result is the same?

Thanks,
Thinh