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From:   Badhri Jagan Sridharan <badhri@google.com>
Date:   Tue, 25 Jan 2022 20:07:51 -0800
Message-ID: <CAPTae5+hkLXmumQrJhV5PW5oRCGhUQwF1tvMQQ2SKjeUhoWtxw@mail.gmail.com>
Subject: Re: [PATCH v2 1/2] usb: typec: tcpm: Do not disconnect while
 receiving VBUS off
To:     Guenter Roeck <linux@roeck-us.net>
Cc:     Heikki Krogerus <heikki.krogerus@linux.intel.com>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        USB <linux-usb@vger.kernel.org>,
        LKML <linux-kernel@vger.kernel.org>,
        Kyle Tso <kyletso@google.com>, stable@vger.kernel.org
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My bad ! Apologies .. fixing it in V3..


On Tue, Jan 25, 2022 at 7:34 PM Guenter Roeck <linux@roeck-us.net> wrote:
>
> On 1/25/22 18:00, Badhri Jagan Sridharan wrote:
> > With some chargers, vbus might momentarily raise above VSAFE5V and fall
> > back to 0V before tcpm gets to read port->tcpc->get_vbus. This will
> > report a VBUS off event causing TCPM to transition to SNK_UNATTACHED
> > where it should be waiting in either SNK_ATTACH_WAIT or SNK_DEBOUNCED
> > state. This patch makes TCPM avoid vbus off events while in
> > SNK_ATTACH_WAIT or SNK_DEBOUNCED state.
> >
> > Stub from the spec:
> >      "4.5.2.2.4.2 Exiting from AttachWait.SNK State
> >      A Sink shall transition to Unattached.SNK when the state of both
> >      the CC1 and CC2 pins is SNK.Open for at least tPDDebounce.
> >      A DRP shall transition to Unattached.SRC when the state of both
> >      the CC1 and CC2 pins is SNK.Open for at least tPDDebounce."
> >
> > [23.194131] CC1: 0 -> 0, CC2: 0 -> 5 [state SNK_UNATTACHED, polarity 0, connected]
> > [23.201777] state change SNK_UNATTACHED -> SNK_ATTACH_WAIT [rev3 NONE_AMS]
> > [23.209949] pending state change SNK_ATTACH_WAIT -> SNK_DEBOUNCED @ 170 ms [rev3 NONE_AMS]
> > [23.300579] VBUS off
> > [23.300668] state change SNK_ATTACH_WAIT -> SNK_UNATTACHED [rev3 NONE_AMS]
> > [23.301014] VBUS VSAFE0V
> > [23.301111] Start toggling
> >
> > Fixes: f0690a25a140b8 ("staging: typec: USB Type-C Port Manager (tcpm)")
> > Cc: stable@vger.kernel.org
> > Signed-off-by: Badhri Jagan Sridharan <badhri@google.com>
>
> Why did you drop the Reviewed-by/Acked-by tags ?
>
> Guenter
>
> > ---
> > Changes since v1:
> > - Fix typos stated by Guenter Roeck.
> > ---
> >   drivers/usb/typec/tcpm/tcpm.c | 3 ++-
> >   1 file changed, 2 insertions(+), 1 deletion(-)
> >
> > diff --git a/drivers/usb/typec/tcpm/tcpm.c b/drivers/usb/typec/tcpm/tcpm.c
> > index 59d4fa2443f2..3bf79f52bd34 100644
> > --- a/drivers/usb/typec/tcpm/tcpm.c
> > +++ b/drivers/usb/typec/tcpm/tcpm.c
> > @@ -5156,7 +5156,8 @@ static void _tcpm_pd_vbus_off(struct tcpm_port *port)
> >       case SNK_TRYWAIT_DEBOUNCE:
> >               break;
> >       case SNK_ATTACH_WAIT:
> > -             tcpm_set_state(port, SNK_UNATTACHED, 0);
> > +     case SNK_DEBOUNCED:
> > +             /* Do nothing, as TCPM is still waiting for vbus to reach VSAFE5V to connect */
> >               break;
> >
> >       case SNK_NEGOTIATE_CAPABILITIES:
>