On Tue, Apr 16, 2024 at 04:48:32PM +0300, Andy Shevchenko wrote:
> On Thu, Apr 11, 2024 at 10:52:36PM +0200, Ferry Toth wrote:
> > Op 11-04-2024 om 18:39 schreef Andy Shevchenko:
> > > On Thu, Apr 11, 2024 at 04:26:37PM +0200, Hardik Gajjar wrote:
> > > > On Wed, Apr 10, 2024 at 08:37:42PM +0300, Andy Shevchenko wrote:
> > > > > On Sun, Apr 07, 2024 at 10:51:51PM +0200, Ferry Toth wrote:
> > > > > > Op 05-04-2024 om 13:38 schreef Hardik Gajjar:
>
> ...
>
> > > > > > Exactly. And this didn't happen before the 2 patches.
> > > > > >
> > > > > > To be precise: /sys/class/net/usb0 is not removed and it is a link, the link
> > > > > > target /sys/devices/pci0000:00/0000:00:11.0/dwc3.0.auto/gadget.0/net/usb0 no
> > > > > > longer exists
> > > > So, it means that the /sys/class/net/usb0 is present, but the symlink is
> > > > broken. In that case, the dwc3 driver should recreate the device, and the
> > > > symlink should become active again
> >
> > Yes, on first enabling gadget (when device mode is activated):
> >
> > root@yuna:~# ls /sys/devices/pci0000:00/0000:00:11.0/dwc3.0.auto/gadget.0/
> > driver net power sound subsystem suspended uevent
> >
> > Then switching to host mode:
> >
> > root@yuna:~# ls /sys/devices/pci0000:00/0000:00:11.0/dwc3.0.auto/gadget.0/
> > ls: cannot access
> > '/sys/devices/pci0000:00/0000:00:11.0/dwc3.0.auto/gadget.0/': No such file
> > or directory
> >
> > Then back to device mode:
> >
> > root@yuna:~# ls /sys/devices/pci0000:00/0000:00:11.0/dwc3.0.auto/gadget.0/
> > driver power sound subsystem suspended uevent
> >
> > net is missing. But, network functions:
> >
> > root@yuna:~# ping 10.42.0.1
> > PING 10.42.0.1 (10.42.0.1): 56 data bytes
> >
> > Mass storage device is created and removed each time as expected.
>
> So, what's the conclusion? Shall we move towards revert of those two changes?
As promised, I have the tested the this patch with the dwc3 gadget. I could not reproduce
the issue.
I can see the usb0 exist all the time and accessible regardless of the role switching of the USB mode (peripheral <-> host)
Following are the logs:
//Host to device
console:/sys/bus/platform/devices/a800000.ssusb # echo "peripheral" > mode
console:/sys/bus/platform/devices/a800000.ssusb # ls a800000.dwc3/gadget/net/
usb0
//device to host
console:/sys/bus/platform/devices/a800000.ssusb # echo "host" > mode
console:/sys/bus/platform/devices/a800000.ssusb # ls a800000.dwc3/gadget/net/
usb0
s a800000.dwc3/gadget/net/usb0 <
addr_assign_type duplex phys_port_name
addr_len flags phys_switch_id
address gro_flush_timeout power
broadcast ifalias proto_down
carrier ifindex queues
carrier_changes iflink speed
carrier_down_count link_mode statistics
carrier_up_count mtu subsystem
dev_id name_assign_type tx_queue_len
dev_port netdev_group type
device operstate uevent
dormant phys_port_id waiting_for_supplier
console:/sys/bus/platform/devices/a800000.ssusb # ifconfig -a usb0
usb0 Link encap:Ethernet HWaddr 3a:8b:63:97:1a:9a
BROADCAST MULTICAST MTU:1500 Metric:1
RX packets:0 errors:0 dropped:0 overruns:0 frame:0
TX packets:0 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:1000
RX bytes:0 TX bytes:0
console:/sys/bus/platform/devices/a800000.ssusb #
I strongly advise against reverting the patch solely based on the observed issue of removing the /sys/class/net/usb0 directory while the usb0 interface remains available.
Instead, I recommend enabling FTRACE to trace the functions involved and identify which faulty call is responsible for removing usb0.
According to current kernel architecture of u_ether driver, only gether_cleanup should remove the usb0 interface along with its kobject and sysfs interface.
I suggest sharing the analysis here to understand why this practice is not followed in your use case or driver ?
I am curious why the driver was developed without adhering to the kernel's gadget architecture.
>
> > > > I have the dwc3 IP base usb controller, Let me check with this patch and
> > > > share result here. May be we need some fix in dwc3
> > Would have been nice if someone could test on other controller as well. But
> > another instance of dwc3 is also very welcome.
> > > It's quite possible, please test on your side.
> > > We are happy to test any fixes if you come up with.
>
> --
> With Best Regards,
> Andy Shevchenko
>
>
