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

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Hi

Op 21-04-2021 om 21:01 schreef Thinh Nguyen:
Ferry Toth wrote:
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@xxxxxxxxxx>
From: John Stultz <john.stultz@xxxxxxxxxx>

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@xxxxxxxxxx/__;!!A4F2R9G_pg!PW9Jbs4wv4a_zKGgZHN0FYrIpfecPX0Ouq9V3d16Yz-9-GSHqZWsfBAF-WkeqLhzN4i3$




[2]
https://urldefense.com/v3/__https://lore.kernel.org/linux-usb/0ba7a6ba-e6a7-9cd4-0695-64fc927e01f1@xxxxxxxxx/__;!!A4F2R9G_pg!PW9Jbs4wv4a_zKGgZHN0FYrIpfecPX0Ouq9V3d16Yz-9-GSHqZWsfBAF-WkeqGeZStt4$





Cc: Andy Shevchenko <andy.shevchenko@xxxxxxxxx>
Cc: Ferry Toth <fntoth@xxxxxxxxx>
Cc: Wesley Cheng <wcheng@xxxxxxxxxxxxxx>
Cc: <stable@xxxxxxxxxxxxxxx>
Fixes: 41ce1456e1db ("usb: dwc3: core: make dwc3_set_mode() work
properly")
Signed-off-by: Yu Chen <chenyu56@xxxxxxxxxx>
Signed-off-by: John Stultz <john.stultz@xxxxxxxxxx>
Signed-off-by: Thinh Nguyen <Thinh.Nguyen@xxxxxxxxxxxx>
---
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: usb1-5: New USB device
      strings: Mfr=1, Product=2, SerialNumber=3kernel: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 dropped191 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://urldefense.com/v3/__https://github.com/andy-shev/linux/files/6346271/first-switch.zip__;!!A4F2R9G_pg!KAmPA0Vw1WUiSxdc5-BKNPyD0klvdr5ucZI3E_C2ojho2rNT9wzMs8HG4qCYSDx89HFE$

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?
 From the info here, it doesn't look like the host platform device was
removed on the first switch. Also, as you pointed it out, the extcon
event was not shown on the first switch either. Without a notification
to switch mode, the dwc3 driver won't do anything. You need to check why
that's the case as I can't help much here.
Thanks, I am looking into our extcon driver now for this.
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://urldefense.com/v3/__https://github.com/andy-shev/linux/files/6346323/lost-connection.zip__;!!A4F2R9G_pg!KAmPA0Vw1WUiSxdc5-BKNPyD0klvdr5ucZI3E_C2ojho2rNT9wzMs8HG4qCYSIuUHRz4$

Nothing obvious stands out as a problem from the dwc3 driver or the
controller. I see a (port) reset after 30 seconds of inactivity, which
is a typical timeout and recovery mechanism in the upperlayer from host.

* Is this a new issue or was it always there?
I've seen it before, but because of all the other issues it wasn't obvious.
* Does turning off LPM help?
I think so, but maybe didn't wait long enough. This I will retest tomorrow evening.
* Are the other gadget functions still work during the 30 seconds
inactivity?
No. The behavior seems same as unplug/plug the cable.

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.

BR,
Thinh



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