Thanks Guenter ! However I don't see a reviewed-by tag :) On Tue, Aug 11, 2020 at 1:18 PM Guenter Roeck <linux@xxxxxxxxxxxx> wrote: > > On 8/11/20 12:39 PM, Badhri Jagan Sridharan wrote: > > 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. > > > > Excellent. Thanks a lot for looking into this! > > Guenter > > >>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; > >>>>> > >>>> >
