Re: [PATCH] usb: core: deattach child device from typec connector on port unbind

[Heikki Krogerus <heikki.krogerus@linux.intel.com>]

On Mon, Jul 27, 2026 at 06:51:36PM +0200, Marco Tormento wrote:
> Hi Heikki,
> 
> On Mon, 27 Jul 2026 at 13:13, Heikki Krogerus
> <heikki.krogerus@linux.intel.com> wrote:
> >
> > We should not need to reverse anything. We can't avoid calling
> > typec_attach() separately from connector_bind() because we can't
> > prevent USB devices from being enumerated before the typec drivers are
> > loaded for example during bootup. But that does not mean we need to
> > call typec_deattach() in connector_unbind().
> >
> > After the USB device is "attached" to the typec connector, the
> > connector device should be pinned down for as long as the USB device
> > exists, but that is not happening. So what both you guys are doing, is
> > working around a problem with the reference count.
> >
> > I can see that most of your commit message is written by some LLM, and
> > the parts that you've added don't usually belong to the commit
> > message. That makes me a bit concerned about how much you actually
> > understand what the code that you are modifying does.
> >
> > Use of LLMs is fine, but you still have understand the code that you
> > modify.
> 
> First of all, thank you for the explanation.
> 
> The commit message definitely sounded over confident, my understanding
> of the issue is summed up here in my first patch submission a year
> ago: https://lore.kernel.org/all/20250720210847.30998-1-mtormento80@gmail.com/
> 
> As I said back then, my experience on kernel code was nearly zero, and
> I was well aware there might be better ways to fix the issue: that's
> also true today.
> 
> What I did a few days ago was to ask AI to analyse my first patch and
> see if it could find a better mitigation.
> It came up with this patch, I read the explanation and it made sense
> for my level of understanding of the matter (which is arguably low,
> unfortunately).
> I checked the code and tested for a while with success, so I submitted
> a new patch and here we are.
> 
> Do you have any suspects yet on where the underlying issue might be?

Right now my gut feeling is that this should be fixed in
drivers/usb/typec/class.c, but I would need to be able to study this
more carefully.

Thanks,

-- 
heikki