Re: [libusb] INVALID_PARAM when reconnecting to device after disconnect

[Karl S. <0x...@gm...>]

On Sat, Jun 29, 2024 at 17:01 Tim Roberts <ti...@pr...> wrote:

> Dean Sands wrote:
> > Tried a dumb thing.
> > The device I'm getting from the hotplug arrival event isn't usable.
> > I open a handle and make a few token attempts to claim the interface.
> > When that fails I close the handle.
> > Then I search for the device again and connect to that.
>
> Are you saying you got it to work?
>
> In general, as soon as you know a device is unusable, you should close
> the handle.  As long as your handle remains open, the kernel cannot
> clean up the remnants of the previous instance, and that can cause
> confusing problems and duplicate instances.


I vaguely recall the problem of engaging a reconnected device without
restarting the app may have been outstanding for years.

If this is the problem and workaround, it would ideally be documented
somewhere in such a way that more applications emerge supporting
reconnection.

I imagine it would help legacy applications a lot to add code that cleans
things up enough to recreate a device the first time it becomes unusable.