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

[Ferry Toth <fntoth@gmail.com>]

Hi

Op 19-04-2021 om 23:23 schreef Thinh Nguyen:
> Ferry Toth wrote:
>> Hi
>>
>> Op 19-04-2021 om 01:03 schreef Thinh Nguyen:
>>> Ferry Toth wrote:
>>>> Hi
>>>>
>>>> Op 17-04-2021 om 16:22 schreef Ferry Toth:
>>>>> Hi
>>>>>
>>>>> Op 17-04-2021 om 04:27 schreef Thinh Nguyen:
>>>>>> 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
>>>>>>> usingxhci_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?
>>>>> I have already gser, eem, mass_storage and uac2 combo. When eem fails,
>>>>> the mass_storage and uac2 don't appear (on KDE you get all kind of
>>>>> popups when they appear).
>>>>>
>>>>> So either all works, or all fails.
>>>>>
>>>>> I'll trace this later today.
>>>> Trace capturing switch from host-> gadget  here
>>>> https://urldefense.com/v3/__https://github.com/andy-shev/linux/files/6329600/5.12-rc7*2Busb-next.zip__;JQ!!A4F2R9G_pg!Oa6XGH3IqY3wwG5KK4FwPuNA0m3q5bRj7N6vdP-y4sAY6mya-96J90NJ0tJnXLOiNwGT$
>>>>
>>>>
>>>> (Issue history:
>>>> https://urldefense.com/v3/__https://github.com/andy-shev/linux/issues/31__;!!A4F2R9G_pg!Oa6XGH3IqY3wwG5KK4FwPuNA0m3q5bRj7N6vdP-y4sAY6mya-96J90NJ0tJnXNc7KgAw$
>>>>
>>>> )
>>>>
>>>> On the PC side this resulted to:
>>>>
>>>> apr 17 18:17:44 delfion kernel: usb 1-5: new high-speed USB device
>>>> number 12 using xhci_hcd
>>>> apr 17 18:17:44 delfion kernel: usb 1-5: New USB device found,
>>>> idVendor=1d6b, idProduct=0104, bcdDevice= 1.00
>>>> apr 17 18:17:44 delfion kernel: usb 1-5: New USB device strings: Mfr=1,
>>>> Product=2, SerialNumber=3
>>>> apr 17 18:17:44 delfion kernel: usb 1-5: Product: USBArmory Gadget
>>>> apr 17 18:17:44 delfion kernel: usb 1-5: Manufacturer: USBArmory
>>>> apr 17 18:17:44 delfion kernel: usb 1-5: SerialNumber: 0123456789abcdef
>>>> apr 17 18:17:49 delfion kernel: usb 1-5: can't set config #1, error -110
>>>>
>>>>
>>>> Thanks for all your help!
>>>>
>>> Looks like it's LPM related again. To confirm, try this:
>>> Disable LPM with this property "snps,usb2-gadget-lpm-disable"
>>> (Note that it's not the same as "snps,dis_enblslpm_quirk")
>> Yes, I confirm this helps.
>>
>> Note: on startup I was in host mode, with gadget cable plugged. The
>> first switch to gadget didn't work, all subsequent switches did work, as
>> well as unplug/plug the cable.
>>
>>> Make sure that your testing kernel has this patch [1]
>>> 475e8be53d04 ("usb: dwc3: gadget: Check for disabled LPM quirk")
>>>
>>> [1]
>>> https://urldefense.com/v3/__https://git.kernel.org/pub/scm/linux/kernel/git/gregkh/usb.git/commit/?h=usb-next&id=475e8be53d0496f9bc6159f4abb3ff5f9b90e8de__;!!A4F2R9G_pg!Mvz1Am6Ka_pOBfD0TmsA3821I05Ti8stMgh5r4XzMwZ9dy1Wan-il-DB4h50DmbaU4Zw$
>>>
>>>
>>> The failure you saw was probably due the gadget function attempting
>>> to start a delayed status stage of the SET_CONFIGURATION request.
>>> By this time, the host already put the device in low power.
>>>
>>> The START_TRANSFER command needs to be executed while the device
>>> is on "ON" state (or U0 if eSS). We shouldn't use dwc->link_state
>>> to check for link state because we only enable link state change
>>> interrupt for some controller versions.
>>>
>>> Once you confirms disabling LPM works, try this fix:
>>>
>>> diff --git a/drivers/usb/dwc3/gadget.c b/drivers/usb/dwc3/gadget.c
>>> index 6227641f2d31..06cdec79244e 100644
>>> --- a/drivers/usb/dwc3/gadget.c
>>> +++ b/drivers/usb/dwc3/gadget.c
>>> @@ -309,10 +309,14 @@ int dwc3_send_gadget_ep_cmd(struct dwc3_ep *dep,
>>> unsigned int cmd,
>>>             if (DWC3_DEPCMD_CMD(cmd) == DWC3_DEPCMD_STARTTRANSFER) {
>>>                   int             needs_wakeup;
>>> +               u8              link_state;
>>>    -               needs_wakeup = (dwc->link_state ==
>>> DWC3_LINK_STATE_U1 ||
>>> -                               dwc->link_state == DWC3_LINK_STATE_U2||
>>> -                               dwc->link_state == DWC3_LINK_STATE_U3);
>>> +               reg = dwc3_readl(dwc->regs, DWC3_DSTS);
>>> +               link_state = DWC3_DSTS_USBLNKST(reg);
>>> +
>>> +               needs_wakeup = (link_state == DWC3_LINK_STATE_U1 ||
>>> +                               link_state == DWC3_LINK_STATE_U2 ||
>>> +                               link_state == DWC3_LINK_STATE_U3);
>>>                     if (unlikely(needs_wakeup)) {
>>>                           ret = __dwc3_gadget_wakeup(dwc);
>>> @@ -1989,6 +1993,8 @@ static int __dwc3_gadget_wakeup(struct dwc3 *dwc)
>>>           case DWC3_LINK_STATE_RESET:
>>>           case DWC3_LINK_STATE_RX_DET:    /* in HS, means Early Suspend */
>>>           case DWC3_LINK_STATE_U3:        /* in HS, means SUSPEND */
>>> +       case DWC3_LINK_STATE_U2:        /* in HS, means Sleep (L1) */
>>> +       case DWC3_LINK_STATE_U1:
>>>           case DWC3_LINK_STATE_RESUME:
>>>                   break;
>>>           default:
>>>
>> Same (good) result as with "snps,usb2-gadget-lpm-disable". Including
>> first switch from host->gadget not working.
>>
> Great! Not sure why the first switch is not working, but it seems like
> we were able to eliminate quite a few issues. If you have more dwc3
> tracepoints, we can take a look further.

I traced but the file is empty. I captured the registers as well. The 
zip file is here:

https://github.com/andy-shev/linux/files/6346271/first-switch.zip

I found the gadget configuration script was not called, which normally 
gets called due to a udev rule:

ACTION=="add", KERNEL=="dwc3.0.auto", SUBSYSTEMS=="udc", 
ATTRS{state}=="not attached", RUN+="/usr/bin/conf-gadget.sh"

So I retried and see  with ~# udevadm monitor:

# flipping the switch from host->gadget

KERNEL[51.824914] remove 
/devices/pci0000:00/0000:00:11.0/dwc3.0.auto/xhci-hcd.2.auto/usb1/1-1/1-1.1/1-1.1:1.0/net/enp0s17u1u1/queues/rx-0 
(queues)
KERNEL[51.825682] remove 
/devices/pci0000:00/0000:00:11.0/dwc3.0.auto/xhci-hcd.2.auto/usb1/1-1/1-1.1/1-1.1:1.0/net/enp0s17u1u1/queues/tx-0 
(queues)
KERNEL[51.826226] remove 
/devices/pci0000:00/0000:00:11.0/dwc3.0.auto/xhci-hcd.2.auto/usb1/1-1/1-1.1/1-1.1:1.0/net/enp0s17u1u1 
(net)
KERNEL[51.836041] unbind 
/devices/pci0000:00/0000:00:11.0/dwc3.0.auto/xhci-hcd.2.auto/usb1/1-1/1-1.1/mdio_bus/usb-001:003/usb-001:003:01 
(mdio_bus)
KERNEL[51.836709] remove 
/devices/pci0000:00/0000:00:11.0/dwc3.0.auto/xhci-hcd.2.auto/usb1/1-1/1-1.1/mdio_bus/usb-001:003/usb-001:003:01 
(mdio_bus)
KERNEL[51.837342] remove 
/devices/pci0000:00/0000:00:11.0/dwc3.0.auto/xhci-hcd.2.auto/usb1/1-1/1-1.1/mdio_bus/usb-001:003 
(mdio_bus)
KERNEL[51.837763] unbind 
/devices/pci0000:00/0000:00:11.0/dwc3.0.auto/xhci-hcd.2.auto/usb1/1-1/1-1.1/1-1.1:1.0 
(usb)
KERNEL[51.838116] remove 
/devices/pci0000:00/0000:00:11.0/dwc3.0.auto/xhci-hcd.2.auto/usb1/1-1/1-1.1/1-1.1:1.0 
(usb)
KERNEL[51.873712] unbind 
/devices/pci0000:00/0000:00:11.0/dwc3.0.auto/xhci-hcd.2.auto/usb1/1-1/1-1.1 
(usb)
KERNEL[51.874000] remove 
/devices/pci0000:00/0000:00:11.0/dwc3.0.auto/xhci-hcd.2.auto/usb1/1-1/1-1.1 
(usb)
KERNEL[51.874207] unbind 
/devices/pci0000:00/0000:00:11.0/dwc3.0.auto/xhci-hcd.2.auto/usb1/1-1/1-1:1.0 
(usb)
KERNEL[51.874431] remove 
/devices/pci0000:00/0000:00:11.0/dwc3.0.auto/xhci-hcd.2.auto/usb1/1-1/1-1:1.0 
(usb)
KERNEL[51.897175] unbind 
/devices/pci0000:00/0000:00:11.0/dwc3.0.auto/xhci-hcd.2.auto/usb1/1-1 (usb)
KERNEL[51.897486] remove 
/devices/pci0000:00/0000:00:11.0/dwc3.0.auto/xhci-hcd.2.auto/usb1/1-1 (usb)

# stopped capture tracepoints here, then switch back to host

KERNEL[253.214406] add 
/devices/pci0000:00/0000:00:11.0/dwc3.0.auto/xhci-hcd.2.auto/usb1/1-1 (usb)
KERNEL[253.263305] change 
/devices/pci0000:00/0000:00:11.0/dwc3.0.auto/xhci-hcd.2.auto/usb1/1-1 (usb)
KERNEL[253.263687] add 
/devices/pci0000:00/0000:00:11.0/dwc3.0.auto/xhci-hcd.2.auto/usb1/1-1/1-1:1.0 
(usb)
KERNEL[253.328354] bind 
/devices/pci0000:00/0000:00:11.0/dwc3.0.auto/xhci-hcd.2.auto/usb1/1-1/1-1:1.0 
(usb)
KERNEL[253.328734] bind 
/devices/pci0000:00/0000:00:11.0/dwc3.0.auto/xhci-hcd.2.auto/usb1/1-1 (usb)
KERNEL[253.699341] add 
/devices/pci0000:00/0000:00:11.0/dwc3.0.auto/xhci-hcd.2.auto/usb1/1-1/1-1.1 
(usb)
KERNEL[253.744911] change 
/devices/pci0000:00/0000:00:11.0/dwc3.0.auto/xhci-hcd.2.auto/usb1/1-1/1-1.1 
(usb)
KERNEL[253.745804] add 
/devices/pci0000:00/0000:00:11.0/dwc3.0.auto/xhci-hcd.2.auto/usb1/1-1/1-1.1/1-1.1:1.0 
(usb)
KERNEL[253.805307] add 
/devices/pci0000:00/0000:00:11.0/dwc3.0.auto/xhci-hcd.2.auto/usb1/1-1/1-1.1/mdio_bus/usb-001:005 
(mdio_bus)
KERNEL[253.812978] add 
/devices/pci0000:00/0000:00:11.0/dwc3.0.auto/xhci-hcd.2.auto/usb1/1-1/1-1.1/mdio_bus/usb-001:005/usb-001:005:01 
(mdio_bus)
KERNEL[253.814318] bind 
/devices/pci0000:00/0000:00:11.0/dwc3.0.auto/xhci-hcd.2.auto/usb1/1-1/1-1.1/mdio_bus/usb-001:005/usb-001:005:01 
(mdio_bus)
KERNEL[253.815386] add 
/devices/pci0000:00/0000:00:11.0/dwc3.0.auto/xhci-hcd.2.auto/usb1/1-1/1-1.1/1-1.1:1.0/net/eth0 
(net)
KERNEL[253.815552] add 
/devices/pci0000:00/0000:00:11.0/dwc3.0.auto/xhci-hcd.2.auto/usb1/1-1/1-1.1/1-1.1:1.0/net/eth0/queues/rx-0 
(queues)
KERNEL[253.815778] add 
/devices/pci0000:00/0000:00:11.0/dwc3.0.auto/xhci-hcd.2.auto/usb1/1-1/1-1.1/1-1.1:1.0/net/eth0/queues/tx-0 
(queues)
KERNEL[253.825279] bind 
/devices/pci0000:00/0000:00:11.0/dwc3.0.auto/xhci-hcd.2.auto/usb1/1-1/1-1.1/1-1.1:1.0 
(usb)
KERNEL[253.825667] bind 
/devices/pci0000:00/0000:00:11.0/dwc3.0.auto/xhci-hcd.2.auto/usb1/1-1/1-1.1 
(usb)

# switch to gadget again

KERNEL[314.212144] remove 
/devices/pci0000:00/0000:00:11.0/dwc3.0.auto/xhci-hcd.2.auto/usb1/1-1/1-1.1/1-1.1:1.0/net/eth0/queues/rx-0 
(queues)
KERNEL[314.212473] remove 
/devices/pci0000:00/0000:00:11.0/dwc3.0.auto/xhci-hcd.2.auto/usb1/1-1/1-1.1/1-1.1:1.0/net/eth0/queues/tx-0 
(queues)
KERNEL[314.214691] remove 
/devices/pci0000:00/0000:00:11.0/dwc3.0.auto/xhci-hcd.2.auto/usb1/1-1/1-1.1/1-1.1:1.0/net/eth0 
(net)

# extcon event didn't show the first time

KERNEL[314.238385] change 
/devices/pci0000:00/0000:00:13.0/INTC100E:00/mrfld_bcove_pwrsrc/extcon/extcon0 
(extcon)
KERNEL[314.238677] unbind 
/devices/pci0000:00/0000:00:11.0/dwc3.0.auto/xhci-hcd.2.auto/usb1/1-1/1-1.1/mdio_bus/usb-001:005/usb-001:005:01 
(mdio_bus)
KERNEL[314.238863] remove 
/devices/pci0000:00/0000:00:11.0/dwc3.0.auto/xhci-hcd.2.auto/usb1/1-1/1-1.1/mdio_bus/usb-001:005/usb-001:005:01 
(mdio_bus)
KERNEL[314.239015] remove 
/devices/pci0000:00/0000:00:11.0/dwc3.0.auto/xhci-hcd.2.auto/usb1/1-1/1-1.1/mdio_bus/usb-001:005 
(mdio_bus)
KERNEL[314.239205] unbind 
/devices/pci0000:00/0000:00:11.0/dwc3.0.auto/xhci-hcd.2.auto/usb1/1-1/1-1.1/1-1.1:1.0 
(usb)
KERNEL[314.239429] remove 
/devices/pci0000:00/0000:00:11.0/dwc3.0.auto/xhci-hcd.2.auto/usb1/1-1/1-1.1/1-1.1:1.0 
(usb)
KERNEL[314.239666] unbind 
/devices/pci0000:00/0000:00:11.0/dwc3.0.auto/xhci-hcd.2.auto/usb2/2-0:1.0 
(usb)
KERNEL[314.239933] remove 
/devices/pci0000:00/0000:00:11.0/dwc3.0.auto/xhci-hcd.2.auto/usb2/2-0:1.0 
(usb)
KERNEL[314.262713] unbind 
/devices/pci0000:00/0000:00:11.0/dwc3.0.auto/xhci-hcd.2.auto/usb2 (usb)
KERNEL[314.263030] unbind 
/devices/pci0000:00/0000:00:11.0/dwc3.0.auto/xhci-hcd.2.auto/usb1/1-1/1-1.1 
(usb)
KERNEL[314.263298] remove 
/devices/pci0000:00/0000:00:11.0/dwc3.0.auto/xhci-hcd.2.auto/usb2 (usb)
KERNEL[314.263569] remove 
/devices/pci0000:00/0000:00:11.0/dwc3.0.auto/xhci-hcd.2.auto/usb1/1-1/1-1.1 
(usb)
KERNEL[314.263815] unbind 
/devices/pci0000:00/0000:00:11.0/dwc3.0.auto/xhci-hcd.2.auto/usb1/1-1/1-1:1.0 
(usb)
KERNEL[314.264042] remove 
/devices/pci0000:00/0000:00:11.0/dwc3.0.auto/xhci-hcd.2.auto/usb1/1-1/1-1:1.0 
(usb)
KERNEL[314.264753] remove 
/devices/pci0000:00/0000:00:11.0/dwc3.0.auto/xhci-hcd.2.auto/usbmon/usbmon2 
(usbmon)
KERNEL[314.265019] unbind 
/devices/pci0000:00/0000:00:11.0/dwc3.0.auto/xhci-hcd.2.auto/usb1/1-1 (usb)
KERNEL[314.265289] remove 
/devices/pci0000:00/0000:00:11.0/dwc3.0.auto/xhci-hcd.2.auto/usb1/1-1 (usb)
KERNEL[314.288792] unbind 
/devices/pci0000:00/0000:00:11.0/dwc3.0.auto/xhci-hcd.2.auto/usb1/1-0:1.0 
(usb)
KERNEL[314.289057] remove 
/devices/pci0000:00/0000:00:11.0/dwc3.0.auto/xhci-hcd.2.auto/usb1/1-0:1.0 
(usb)
KERNEL[314.289327] unbind 
/devices/pci0000:00/0000:00:11.0/dwc3.0.auto/xhci-hcd.2.auto/usb1 (usb)
KERNEL[314.289661] remove 
/devices/pci0000:00/0000:00:11.0/dwc3.0.auto/xhci-hcd.2.auto/usb1 (usb)
KERNEL[314.647375] remove 
/devices/pci0000:00/0000:00:11.0/dwc3.0.auto/xhci-hcd.2.auto/usbmon/usbmon1 
(usbmon)
KERNEL[314.647816] unbind 
/devices/pci0000:00/0000:00:11.0/dwc3.0.auto/xhci-hcd.2.auto (platform)
KERNEL[314.648143] remove   /kernel/software_nodes/node1 (software_nodes)
KERNEL[314.648672] remove 
/devices/pci0000:00/0000:00:11.0/dwc3.0.auto/xhci-hcd.2.auto (platform)

# here is the event we were waiting for

KERNEL[314.649158] add 
/devices/pci0000:00/0000:00:11.0/dwc3.0.auto/udc/dwc3.0.auto (udc)

# after this gadget devices appear normally

Maybe this issue is due to extcon missing the event?

>> After a 2 - 4 minutes the connection is dropped and reconnected.
> Does this occur with LPM disabled also? We can review this issue further
> with more dwc3 tracepoints.

I captured connection dropping and reconnecting in this fairly long 
trace near the end of the file:

https://github.com/andy-shev/linux/files/6346323/lost-connection.zip


>
>> On the gadget end journal shows:
>>
>> Apr 19 22:08:42 yuna systemd-networkd[507]: usb0: Lost carrier
>> Apr 19 22:08:42 yuna systemd-journald[417]: Forwarding to syslog missed
>> 1 messages.
>> Apr 19 22:08:42 yuna systemd-timesyncd[469]: No network connectivity,
>> watching for changes.
>> Apr 19 22:08:42 yuna kernel: IPv6: ADDRCONF(NETDEV_CHANGE): usb0: link
>> becomes ready
>> Apr 19 22:08:42 yuna kernel[480]: [  624.382929] IPv6:
>> ADDRCONF(NETDEV_CHANGE): usb0: link becomes ready
>> Apr 19 22:08:42 yuna systemd-networkd[507]: usb0: Gained carrier
>> Apr 19 22:08:44 yuna systemd-networkd[507]: usb0: Gained IPv6LL
>> Apr 19 22:08:44 yuna systemd-timesyncd[469]: Network configuration
>> changed, trying to establish connection.
>> Apr 19 22:08:57 yuna systemd-timesyncd[469]: Initial synchronization to
>> time server 216.239.35.8:123 (time3.google.com).
>>
>> So, drops and immediately reconnects.
>>
>  From the look at the log here, it seems to be a reset from host (and an
> issue at the protocol level) unrelated to dwc3 driver or the controller.
> Hopefully and maybe we can get more clues from dwc3 tracepoints.
>
> Thanks,
> Thinh