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From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org,
        Heikki Krogerus <heikki.krogerus@linux.intel.com>,
        Badhri Jagan Sridharan <badhri@google.com>
Subject: [PATCH 5.15 063/171] usb: typec: tcpm: Do not disconnect when receiving VSAFE0V
Date:   Mon, 31 Jan 2022 11:55:28 +0100
Message-Id: <20220131105232.167332623@linuxfoundation.org>
In-Reply-To: <20220131105229.959216821@linuxfoundation.org>
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From: Badhri Jagan Sridharan <badhri@google.com>

commit 746f96e7d6f7a276726860f696671766bfb24cf0 upstream.

With some chargers, vbus might momentarily raise above VSAFE5V and fall
back to 0V causing VSAFE0V to be triggered. This will
will report a VBUS off event causing TCPM to transition to
SNK_UNATTACHED state where it should be waiting in either SNK_ATTACH_WAIT
or SNK_DEBOUNCED state. This patch makes TCPM avoid VSAFE0V 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: 28b43d3d746b8 ("usb: typec: tcpm: Introduce vsafe0v for vbus")
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/20220122015520.332507-2-badhri@google.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 drivers/usb/typec/tcpm/tcpm.c |    4 ++++
 1 file changed, 4 insertions(+)

--- a/drivers/usb/typec/tcpm/tcpm.c
+++ b/drivers/usb/typec/tcpm/tcpm.c
@@ -5264,6 +5264,10 @@ static void _tcpm_pd_vbus_vsafe0v(struct
 	case PR_SWAP_SNK_SRC_SOURCE_ON:
 		/* Do nothing, vsafe0v is expected during transition */
 		break;
+	case SNK_ATTACH_WAIT:
+	case SNK_DEBOUNCED:
+		/*Do nothing, still waiting for VSAFE5V for connect */
+		break;
 	default:
 		if (port->pwr_role == TYPEC_SINK && port->auto_vbus_discharge_enabled)
 			tcpm_set_state(port, SNK_UNATTACHED, 0);