ODROID-C1/-C2 USB Detection only triggered by some devices
Alan Stern
stern at rowland.harvard.edu
Mon Jun 28 07:24:18 PDT 2021
On Sun, Jun 27, 2021 at 09:24:45PM -0400, Matt Corallo wrote:
>
>
> On 6/27/21 21:16, Alan Stern wrote:
> > You mean that only devices in the first group are affected by this bug?
> > Devices in the second group are always detected correctly regardless of
> > what else is plugged in? (This contradicts what you wrote above.)
>
>
> Correct. Ignoring hotplug (ie on fresh boot or lsusb -vvv), the devices in
> the second group work great. The devices in the first group do too, but only
> if a device from the second group is present.
Okay. You can try collecting some usbmon traces to see what's going on.
First test: Boot with nothing plugged in, start a usbmon trace for bus 0
(cat /sys/kernel/debug/usb/usbmon/0u >mon1.txt), plug in a first-group
device, run lsusb -v to trigger enumeration, and then kill the "cat"
process.
Second test: Same as the first except that you boot with a second-group
device already plugged in.
The differences between the two traces may indicate where the problem
is.
Alan Stern
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