On Tue, Aug 11, 2020 at 11:45 AM Guenter Roeck <linux@xxxxxxxxxxxx> wrote: > > On Tue, Aug 11, 2020 at 11:24:07AM -0700, Badhri Jagan Sridharan wrote: > > On Mon, Aug 10, 2020 at 6:51 PM Guenter Roeck <linux@xxxxxxxxxxxx> wrote: > > > > > > On 8/10/20 6:11 PM, Badhri Jagan Sridharan wrote: > > > >>From the spec: > > > > "7.1.5 Response to Hard Resets > > > > Hard Reset Signaling indicates a communication failure has occurred and > > > > the Source Shall stop driving VCONN, Shall remove Rp from the VCONN pin > > > > and Shall drive VBUS to vSafe0V as shown in Figure 7-9. The USB connection > > > > May reset during a Hard Reset since the VBUS voltage will be less than > > > > vSafe5V for an extended period of time. After establishing the vSafe0V > > > > voltage condition on VBUS, the Source Shall wait tSrcRecover before > > > > re-applying VCONN and restoring VBUS to vSafe5V. A Source Shall conform > > > > to the VCONN timing as specified in [USB Type-C 1.3]." > > > > > > > > Signed-off-by: Badhri Jagan Sridharan <badhri@xxxxxxxxxx> > > > > --- > > > > drivers/usb/typec/tcpm/tcpm.c | 16 +++++++++++++--- > > > > 1 file changed, 13 insertions(+), 3 deletions(-) > > > > > > > > diff --git a/drivers/usb/typec/tcpm/tcpm.c b/drivers/usb/typec/tcpm/tcpm.c > > > > index 3ef37202ee37..e41c4e5d3c71 100644 > > > > --- a/drivers/usb/typec/tcpm/tcpm.c > > > > +++ b/drivers/usb/typec/tcpm/tcpm.c > > > > @@ -3372,13 +3372,19 @@ static void run_state_machine(struct tcpm_port *port) > > > > tcpm_set_state(port, SNK_HARD_RESET_SINK_OFF, 0); > > > > break; > > > > case SRC_HARD_RESET_VBUS_OFF: > > > > - tcpm_set_vconn(port, true); > > > > + /* > > > > + * 7.1.5 Response to Hard Resets > > > > + * Hard Reset Signaling indicates a communication failure has occurred and the > > > > + * Source Shall stop driving VCONN, Shall remove Rp from the VCONN pin and Shall > > > > + * drive VBUS to vSafe0V as shown in Figure 7-9. > > > > + */ > > > > + tcpm_set_vconn(port, false); > > > > tcpm_set_vbus(port, false); > > > > tcpm_set_roles(port, port->self_powered, TYPEC_SOURCE, > > > > tcpm_data_role_for_source(port)); > > > > - tcpm_set_state(port, SRC_HARD_RESET_VBUS_ON, PD_T_SRC_RECOVER); > > > > > > I am a bit concerned about this. If I understand correctly, it means that > > > we won't turn VBUS back on unless a SRC_HARD_RESET_VBUS_OFF PD event is received. > > > Is that correct ? What happens if that event is never received ? > > > > > > Thanks, > > > Guenter > > > > The term PD event is a little ambiguous to me. Trying to summarize the workflow. > > Lower level tcpc driver would have to call tcpm_vbus_change which > > would in-turn trigger TCPM_VBUS_EVENT > > and queries port->tcpc->get_vbus to get the vbus status. It is not > > really a PD protocol driven event hence the > > confusion. > > > > "What happens if that event is never received ?" > > Yeah TCPM would be in SRC_HARD_RESET_VBUS_OFF till the tcpc calls the > > tcpm_vbus_change. > > Do you suspect that existing tcpc would not have the capability to > > monitor vbus status while sourcing and call tcpm_vbus_change? > > > That, or the driver might be buggy, or the hardware does't signal a status > update, or the update gets lost. I think we should have some backup, > to trigger if the event is not received in a reasonable amout of time. > I don't know if the specification has some kind of maximum limit. If > not, we should still have something > > Thanks, > Guenter Got it ! The specification actually has a bound for vbus off. tSafe0V - Time to reach vSafe0V max - 650ms. (PD_T_SAFE_0V). So I will bound it to that. >From Table 7-12 Sequence Description for a Source Initiated Hard Reset: 4.Policy Engine waits tPSHardReset after sending Hard Reset Signaling and then tells the Device Policy Manager to instruct the power supply to perform a Hard Reset. The transition to vSafe0V Shall occur within tSafe0V (t2). 5 After tSrcRecover the Source applies power to VBUS in an attempt to re-establish communication with the Sink and resume USB Default Operation. The transition to vSafe5V Shall occur within tSrcTurnOn (t4). Thanks, Badhri > > > Thanks, > > Badhri > > > > > > > > break; > > > > case SRC_HARD_RESET_VBUS_ON: > > > > + tcpm_set_vconn(port, true); > > > > tcpm_set_vbus(port, true); > > > > port->tcpc->set_pd_rx(port->tcpc, true); > > > > tcpm_set_attached_state(port, true); > > > > @@ -3944,7 +3950,11 @@ static void _tcpm_pd_vbus_off(struct tcpm_port *port) > > > > tcpm_set_state(port, SNK_HARD_RESET_WAIT_VBUS, 0); > > > > break; > > > > case SRC_HARD_RESET_VBUS_OFF: > > > > - tcpm_set_state(port, SRC_HARD_RESET_VBUS_ON, 0); > > > > + /* > > > > + * After establishing the vSafe0V voltage condition on VBUS, the Source Shall wait > > > > + * tSrcRecover before re-applying VCONN and restoring VBUS to vSafe5V. > > > > + */ > > > > + tcpm_set_state(port, SRC_HARD_RESET_VBUS_ON, PD_T_SRC_RECOVER); > > > > break; > > > > case HARD_RESET_SEND: > > > > break; > > > > > > >
