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    Subject[PATCH 5.16 082/200] usb: typec: tcpm: Do not disconnect while receiving VBUS off
    Date
    From: Badhri Jagan Sridharan <badhri@google.com>

    commit 90b8aa9f5b09edae6928c0561f933fec9f7a9987 upstream.

    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
    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
    Acked-by: Heikki Krogerus <heikki.krogerus@linux.intel.com>
    Signed-off-by: Badhri Jagan Sridharan <badhri@google.com>
    Link: https://lore.kernel.org/r/20220122015520.332507-1-badhri@google.com
    Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
    ---
    drivers/usb/typec/tcpm/tcpm.c | 3 ++-
    1 file changed, 2 insertions(+), 1 deletion(-)

    --- 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 tcp
    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 reaach VSAFE5V to connect */
    break;

    case SNK_NEGOTIATE_CAPABILITIES:

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