Re: [PATCH] platform/chrome: cros_ec_typec: Skip Type-C mux handling in EC-driven devices

[Andrei Kuchynski]

On Tue, Mar 3, 2026 at 10:54 AM Diogo Ivo <diogo.ivo@xxxxxxxxxxxxxxxxxx> wrote:
>
> Hi Andrei, thanks for testing.
>
> On 3/3/26 07:17, Andrei Kuchynski wrote:
> > Hi Diogo,
> >
> > On Thu, Feb 5, 2026 at 11:04 AM Diogo Ivo <diogo.ivo@xxxxxxxxxxxxxxxxxx> wrote:
> >>
> >> Currently the code assumes that the EC firmware will leave Type-C mux
> >> handling logic to the AP, exposing an interface to query and change the
> >> mux state via a request from the AP. However, in devices such as Smaug
> >> the EC automatically takes care of mux configuration and only USB role
> >> switching needs to be handled by the AP. In fact, in such devices this
> >> interface is not exposed by the EC making the whole process fail,
> >> including role switching.
> >>
> >> Fix this by first separating Type-C mux handling and USB role switching,
> >> explicitly querying the behaviour of the EC and execute each part
> >> conditionally according to what the EC reported.
> >>
> >> Signed-off-by: Diogo Ivo <diogo.ivo@xxxxxxxxxxxxxxxxxx>
> >> ---
> >>   drivers/platform/chrome/cros_ec_typec.c | 49 +++++++++++++++++++++++----------
> >>   drivers/platform/chrome/cros_ec_typec.h |  2 +-
> >>   2 files changed, 35 insertions(+), 16 deletions(-)
> >>
> >> diff --git a/drivers/platform/chrome/cros_ec_typec.c b/drivers/platform/chrome/cros_ec_typec.c
> >> index b712bcff6fb2..bd7e6c365cab 100644
> >> --- a/drivers/platform/chrome/cros_ec_typec.c
> >> +++ b/drivers/platform/chrome/cros_ec_typec.c
> >> @@ -751,11 +751,10 @@ static int cros_typec_configure_mux(struct cros_typec_data *typec, int port_num,
> >>          }
> >>
> >>          /* No change needs to be made, let's exit early. */
> >> -       if (port->mux_flags == resp.flags && port->role == pd_ctrl->role)
> >> +       if (port->mux_flags == resp.flags)
> >>                  return 0;
> >>
> >>          port->mux_flags = resp.flags;
> >> -       port->role = pd_ctrl->role;
> >>
> >>          if (port->mux_flags == USB_PD_MUX_NONE) {
> >>                  ret = cros_typec_usb_disconnect_state(port);
> >> @@ -771,12 +770,6 @@ static int cros_typec_configure_mux(struct cros_typec_data *typec, int port_num,
> >>          if (ret)
> >>                  return ret;
> >>
> >> -       ret = usb_role_switch_set_role(typec->ports[port_num]->role_sw,
> >> -                                       pd_ctrl->role & PD_CTRL_RESP_ROLE_DATA
> >> -                                       ? USB_ROLE_HOST : USB_ROLE_DEVICE);
> >> -       if (ret)
> >> -               return ret;
> >> -
> >>          if (port->mux_flags & USB_PD_MUX_USB4_ENABLED) {
> >>                  ret = cros_typec_enable_usb4(typec, port_num, pd_ctrl);
> >>          } else if (port->mux_flags & USB_PD_MUX_TBT_COMPAT_ENABLED) {
> >> @@ -822,6 +815,25 @@ static int cros_typec_configure_mux(struct cros_typec_data *typec, int port_num,
> >>          return ret;
> >>   }
> >>
> >> +static int cros_typec_set_role(struct cros_typec_data *typec, int port_num,
> >> +                              struct ec_response_usb_pd_control_v1 *resp)
> >> +{
> >> +       enum usb_role cur_role = usb_role_switch_get_role(typec->ports[port_num]->role_sw);
> >> +       enum usb_role role = resp->role & PD_CTRL_RESP_ROLE_DATA ? USB_ROLE_HOST :
> >> +                                                                  USB_ROLE_DEVICE;
> >> +       bool connected = resp->enabled & PD_CTRL_RESP_ENABLED_CONNECTED;
> >> +       int ret;
> >> +
> >> +       if (!connected || cur_role == role)
> >> +               return 0;
> >> +
> >> +       ret = usb_role_switch_set_role(typec->ports[port_num]->role_sw, role);
> >> +       if (ret)
> >> +               dev_err(typec->dev, "Failed USB role switch, err = %d\n", ret);
> >
> > While testing on Brya, I've got a role switch failure:
> > cros-ec-typec GOOG0014:00: Failed USB role switch, err = -22
> > cros-ec-typec GOOG0014:00: Update failed for port: 1
> >
> > Steps to reproduce: deactivate any alt-mode.
>
> I'm unsure of what you mean by this, could you clarify?
>

The cros_ec_typec driver supports DisplayPort and Thunderbolt alternate
modes. During altmode activation or deactivation, the driver handles
Embedded Controller (EC) events via the cros_typec_port_update.

The `active` sysfs attribute is used to initiate these processes; writing 0
to `active` will exit DP or TBT alternate mode.

Thanks,
Andrei