Re: resetting a usb com port?

[Greg Troxel <gdt%lexort.com@localhost>]

mlh%goathill.org@localhost (MLH) writes:

> I am programming some esp32s and every now and then the port locks up from
> an error and I can't find a way to reset it properly.
>
> For example:
>
> [ 651173.2591532] uchcom0 at uhub1 port 9
> [ 651173.2591532] uchcom0: QinHeng Electronics (0x1a86) USB Serial (0x7523), rev 1.10/2.64, addr 3
> [ 651173.2691535] ucom0 at uchcom0
> [ 651197.0392490] ucom0: detached
> [ 651197.0392490] uchcom0: detached
> [ 651197.0392490] uchcom0: at uhub1 port 9 (addr 3) disconnected
> [ 651204.6892798] uhub1: device problem, disabling port 9
> [ 651246.6894490] uhub1: device problem, disabling port 9
> [ 651247.2094511] uhub1: device problem, disabling port 9
>
> Is there a way to reset ucom0 without having to reboot ?

ucom0 is surely not the problem.  It's a logical device attached to
uchcom0.

In the above sequence, did you unplug thecable at 651197?  What happened
at 651204?  Was that plugging in a different ESP32?

My impression is that the problem is the hub (and specifically the port
on it), and that even unplugging and replugging the device will not
help.

I think I've been able to unplug a hub (e.g. thinkpad keyboard) and have
that hub replugged and be ok.  You might try interposing a hub and on
flakiness, unplug everything from the hub, unplug the hub, wait 5s, plug
back in.

Did you try plugging the cable into a different port?