Re: [PATCH v2] usb: typec: tcpm: advance vdm_discovery_state on Discover Identity Not_Supported

[RD Babiera]

Thanks for tagging me here Heikki.

On Tue, Sep 22, 2026 at 3:50 AM Heikki Krogerus
<heikki.krogerus@xxxxxxxxxxxxxxx> wrote:
>
> +RD
>
> On Wed, Sep 16, 2026 at 12:39:57PM +0800, Xu Yang wrote:
> > From: Xu Yang <xu.yang_2@xxxxxxx>
> >
> > Commit Fixes: 205dc9cb39f5 ("usb: typec: tcpm: implement retry mechanism
> > for Discover Identity VDMs") advances vdm_discovery_state to
> > VDM_DISCOVERY_COMPLETE when a CMDT_RSP_NAK is received, but it does not
> > advance the state when a non-modal port returns PD_CTRL_NOT_SUPP.
> >
> > This can re-arm another vdm_discovery_work if the port is going to
> > respond with PD_CTRL_NOT_SUPP to the partner.
> >
> >   tcpm_pd_handle_msg(port, PD_MSG_CTRL_NOT_SUPP, NONE_AMS);
> >     tcpm_queue_message();
> >       mod_tcpm_delayed_work();
> >         tcpm_state_machine_work()
> >           tcpm_send_queued_message()  -> send PD_MSG_CTRL_NOT_SUPP
> >           run_state_machine()
> >             case SRC_READY:
> >             case SNK_READY:
> >               mod_vdm_discovery_delayed_work(port, 0);
> >
> > If both the port and its partner do not support modal operation, they
> > will send DISCOVER_IDENTITY to each other infinitely.
> >
> > Advance vdm_discovery_state to VDM_DISCOVERY_COMPLETE in this path as
> > well. In particular, update the state to VDM_DISCOVERY_COMPLETE if it comes
> > from the port partner, and to VDM_DISCOVERY_CABLE_IDENT if it comes from a
> > cable.
> >
> > Fixes: 205dc9cb39f5 ("usb: typec: tcpm: implement retry mechanism for Discover Identity VDMs")
> > Signed-off-by: Xu Yang <xu.yang_2@xxxxxxx>

Reviewed-by: RD Babiera <rdbabiera@xxxxxxxxxx>

> >
> > ---
> > Changes in v2:
> >  - cover a cable returns PD_CTRL_NOT_SUPP case reported by sashiko

PD Spec indicates that unsupported cable VDMs get ignored, but it is
very much valid to keep the filter in case a non-compliant cable returns
Not_Supported.

> >  - kick off vdm_discovery work to continue working
> >  - correct previous wrong fix commit id
> > ---
> >  drivers/usb/typec/tcpm/tcpm.c | 10 ++++++++++
> >  1 file changed, 10 insertions(+)
> >
> > diff --git a/drivers/usb/typec/tcpm/tcpm.c b/drivers/usb/typec/tcpm/tcpm.c
> > index 2d6b14aa2085..5cea820e00c4 100644
> > --- a/drivers/usb/typec/tcpm/tcpm.c
> > +++ b/drivers/usb/typec/tcpm/tcpm.c
> > @@ -3891,6 +3891,16 @@ static void tcpm_pd_ctrl_request(struct tcpm_port *port,
> >               case SRC_READY:
> >               case SNK_READY:
> >                       if (port->vdm_state > VDM_STATE_READY) {
> > +                             if (port->ams == DISCOVER_IDENTITY) {
> > +                                     if (rx_sop_type == TCPC_TX_SOP) {
> > +                                             tcpm_update_vdm_discovery_state(port,
> > +                                                             VDM_DISCOVERY_COMPLETE);
> > +                                     } else if (rx_sop_type == TCPC_TX_SOP_PRIME) {
> > +                                             tcpm_update_vdm_discovery_state(port,
> > +                                                             VDM_DISCOVERY_CABLE_IDENT);
> > +                                             mod_vdm_discovery_delayed_work(port, 0);
> > +                                     }
> > +                             }
> >                               port->vdm_state = VDM_STATE_DONE;
> >                               if (tcpm_vdm_ams(port))
> >                                       tcpm_ams_finish(port);
> > --
> > 2.34.1
>
> --
> heikki

Best,
RD