USB Type-C Port Manager API concern

[Mats Karrman]

Hi Guenter,

From a previous thread:

On 03/08/2017 02:38 AM, Guenter Roeck wrote:
> On 03/07/2017 02:30 PM, Mats Karrman wrote:
> [ ... ]
>
> > I'm still struggling to catch up on what you guys have been up to 
> > during the
> > last year or so :-) and came across some patches of Guenter from last 
> > October:
> >
> > http://www.mail-archive.com/linux-kernel@xxxxxxxxxxxxxxx/msg1243527.html
> >
> > What happened to them? Has there been any progress since then?
>
> Updates to keep in sync with API changes, bug fixes, and minor 
> improvements,
> for the most part. I can post a current version if there is interest.
> The latest version is also available from
> https://chromium-review.googlesource.com/#/c/389917/

I'm working on a tcpi driver and have some concern about the tcpm api.
The tcpm_register_port() is typically called from the probe function of
tcpi driver where the tcpm_port reference returned is stored in the
driver private data. The problem I ran into is that tcpm_register_port()
calls back to the not yet fully initialized tcpi driver, causing null-
pointer dereferences. This could of course be solved by extra logic in
the tcpi driver but I think it would be more elegant if the registration
of a port could be free of premature callbacks. E.g. it could be required
that the tcpi driver probe called tcpm_tcpc_reset() once it's done
initializing or the necessary data could be supplied in the call to
tcpm_register_port().
What do you think?

BR,
Mats