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    SubjectRe: [PATCH v1] usb: typec: tcpm: Fix TDA 2.2.1.1 and TDA 2.2.1.2 failures
    On Tue, Aug 11, 2020 at 6:44 PM Guenter Roeck <linux@roeck-us.net> wrote:
    >
    > On 8/11/20 6:08 PM, Badhri Jagan Sridharan wrote:
    > > Yes I did ! https://lkml.org/lkml/2020/8/11/788 !
    > >
    > > For me gmail is grouping V1 and V2 patches in the same thread so
    > > thought you saw the v2 patch :P
    > >
    >
    > You copied me on v1, but not on v2. I am not on any of the mailing lists
    > you sent v2 to, so I did not see it.
    >
    > Guenter

    My bad ! Apologies Guenter ! Screwed up while performing the git
    send-email command.
    Will make sure that I double check next time.

    Thanks,
    Badhri

    >
    > > Thanks,
    > > Badhri
    > >
    > > On Tue, Aug 11, 2020 at 5:36 PM Guenter Roeck <linux@roeck-us.net> wrote:
    > >>
    > >> On 8/11/20 4:21 PM, Badhri Jagan Sridharan wrote:
    > >>> Thanks Guenter ! However I don't see a reviewed-by tag :)
    > >>>
    > >>
    > >> Confused. Did you send a v2 with the changes we discussed ?
    > >> I didn't see that.
    > >>
    > >> Thanks,
    > >> Guenter
    > >>
    > >>> On Tue, Aug 11, 2020 at 1:18 PM Guenter Roeck <linux@roeck-us.net> wrote:
    > >>>>
    > >>>> On 8/11/20 12:39 PM, Badhri Jagan Sridharan wrote:
    > >>>>> On Tue, Aug 11, 2020 at 11:45 AM Guenter Roeck <linux@roeck-us.net> 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@roeck-us.net> 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@google.com>
    > >>>>>>>>> ---
    > >>>>>>>>> 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;
    > >>>>>>>>>
    > >>>>>>>>
    > >>>>
    > >>
    >

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