Re: [RFC][PATCH 2/3] usb: roles: Add usb role switch notifier.

[Hans de Goede]

Hi,

On 18-10-2019 07:55, John Stultz wrote:
> On Wed, Oct 16, 2019 at 12:27 AM Hans de Goede <hdegoede@xxxxxxxxxx> wrote:
> > On 10/15/19 7:39 AM, John Stultz wrote:
> > > On Thu, Oct 3, 2019 at 1:51 PM Hans de Goede <hdegoede@xxxxxxxxxx> wrote:
> > > > On 03-10-2019 22:37, John Stultz wrote:
> > > > > Fair point. I'm sort of taking a larger patchset and trying to break
> > > > > it up into more easily reviewable chunks, but I guess here I mis-cut.
> > > > >
> > > > > The user is the hikey960 gpio hub driver here:
> > > > >      https://git.linaro.org/people/john.stultz/android-dev.git/commit/?id=b06158a2d3eb00c914f12c76c93695e92d9af00f
> > > >
> > > > Hmm, that seems to tie the TypeC data-role to the power-role, which
> > > > is not going to work with role swapping.
> > >
> > > Thanks again for the feedback here. Sorry for the slow response. Been
> > > reworking some of the easier changes but am starting to look at how to
> > > address your feedback here.
> > >
> > > > What is controlling the usb-role-switch, and thus ultimately
> > > > causing the notifier you are suggesting to get called ?
> > >
> > > The tcpm_mux_set() call via tcpm_state_machine_work()
> > >
> > > > Things like TYPEC_VBUS_POWER_OFF and TYPEC_VBUS_POWER_ON
> > > > really beg to be modeled as a regulator and then the
> > > > Type-C controller (using e.g. the drivers/usb/typec/tcpm/tcpm.c
> > > > framework) can use that regulator to control things.
> > > > in case of the tcpm.c framework it can then use that
> > > > regulator to implement the set_vbus callback.
> > >
> > > So I'm looking at the bindings and I'm not sure exactly how to tie a
> > > regulator style driver into the tcpm for this?
> > > Looking at the driver I just see this commented out bit:
> > >      https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/drivers/usb/typec/tcpm/tcpm.c#n3075
> > >
> > > Do you happen to have a pointer to something closer to what you are describing?
> >
> > Look at the tcpm_set_vbus implementation in drivers/usb/typec/tcpm/fusb302.c
> > you need to do something similar in your Type-C controller driver and
> > export the GPIO as as a gpio-controlled regulator and tie the regulator to
> > the connector.
>
> Thanks for the suggestion, I really appreciate it! One more question
> though, since I'm using the tcpci_rt1711h driver, which re-uses the
> somewhat sparse tcpci.c implementation, would you recommend trying to
> add generic regulator support to the tcpci code or trying to extend
> the implementation somehow allow the tcpci_rt1711h driver replace just
> the set_vbus function?

I have the feeling that this is more of a question for Heikki.

My first instinct is: if you are using tcpci can't you put all
the hacks you need for the usb connection shared between hub
and type-c in your firmware ?

Regards,

Hans