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Date:   Fri, 21 May 2021 21:01:20 +0800
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Subject: [PATCH 1/2] usb: typec: tcpm: Properly interrupt VDM AMS
From:   Kyle Tso <kyletso@google.com>
To:     linux@roeck-us.net, heikki.krogerus@linux.intel.com,
        gregkh@linuxfoundation.org
Cc:     badhri@google.com, linux-usb@vger.kernel.org,
        linux-kernel@vger.kernel.org, Kyle Tso <kyletso@google.com>
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Precedence: bulk

When a VDM AMS is interrupted by Messages other than VDM, the AMS needs
to be finished properly. Also start a VDM AMS if receiving SVDM Commands
from the port partner to complement the functionality of tcpm_vdm_ams().

Fixes: 0908c5aca31e ("usb: typec: tcpm: AMS and Collision Avoidance")
Signed-off-by: Kyle Tso <kyletso@google.com>
---
 drivers/usb/typec/tcpm/tcpm.c | 30 ++++++++++++++++++++++++++++++
 1 file changed, 30 insertions(+)

diff --git a/drivers/usb/typec/tcpm/tcpm.c b/drivers/usb/typec/tcpm/tcpm.c
index 64133e586c64..deb8a9d01f73 100644
--- a/drivers/usb/typec/tcpm/tcpm.c
+++ b/drivers/usb/typec/tcpm/tcpm.c
@@ -1550,6 +1550,8 @@ static int tcpm_pd_svdm(struct tcpm_port *port, struct typec_altmode *adev,
 			if (PD_VDO_SVDM_VER(p[0]) < svdm_version)
 				typec_partner_set_svdm_version(port->partner,
 							       PD_VDO_SVDM_VER(p[0]));
+
+			tcpm_ams_start(port, DISCOVER_IDENTITY);
 			/* 6.4.4.3.1: Only respond as UFP (device) */
 			if (port->data_role == TYPEC_DEVICE &&
 			    port->nr_snk_vdo) {
@@ -1568,14 +1570,19 @@ static int tcpm_pd_svdm(struct tcpm_port *port, struct typec_altmode *adev,
 			}
 			break;
 		case CMD_DISCOVER_SVID:
+			tcpm_ams_start(port, DISCOVER_SVIDS);
 			break;
 		case CMD_DISCOVER_MODES:
+			tcpm_ams_start(port, DISCOVER_MODES);
 			break;
 		case CMD_ENTER_MODE:
+			tcpm_ams_start(port, DFP_TO_UFP_ENTER_MODE);
 			break;
 		case CMD_EXIT_MODE:
+			tcpm_ams_start(port, DFP_TO_UFP_EXIT_MODE);
 			break;
 		case CMD_ATTENTION:
+			tcpm_ams_start(port, ATTENTION);
 			/* Attention command does not have response */
 			*adev_action = ADEV_ATTENTION;
 			return 0;
@@ -2287,6 +2294,12 @@ static void tcpm_pd_data_request(struct tcpm_port *port,
 	bool frs_enable;
 	int ret;
 
+	if (tcpm_vdm_ams(port) && type != PD_DATA_VENDOR_DEF) {
+		port->vdm_state == VDM_STATE_ERR_BUSY;
+		tcpm_ams_finish(port);
+		mod_vdm_delayed_work(port, 0);
+	}
+
 	switch (type) {
 	case PD_DATA_SOURCE_CAP:
 		for (i = 0; i < cnt; i++)
@@ -2459,6 +2472,16 @@ static void tcpm_pd_ctrl_request(struct tcpm_port *port,
 	enum pd_ctrl_msg_type type = pd_header_type_le(msg->header);
 	enum tcpm_state next_state;
 
+	/*
+	 * Stop VDM state machine if interrupted by other Messages while NOT_SUPP is allowed in
+	 * VDM AMS if waiting for VDM responses and will be handled later.
+	 */
+	if (tcpm_vdm_ams(port) && type != PD_CTRL_NOT_SUPP && type != PD_CTRL_GOOD_CRC) {
+		port->vdm_state = VDM_STATE_ERR_BUSY;
+		tcpm_ams_finish(port);
+		mod_vdm_delayed_work(port, 0);
+	}
+
 	switch (type) {
 	case PD_CTRL_GOOD_CRC:
 	case PD_CTRL_PING:
@@ -2717,6 +2740,13 @@ static void tcpm_pd_ext_msg_request(struct tcpm_port *port,
 	enum pd_ext_msg_type type = pd_header_type_le(msg->header);
 	unsigned int data_size = pd_ext_header_data_size_le(msg->ext_msg.header);
 
+	/* stopping VDM state machine if interrupted by other Messages */
+	if (tcpm_vdm_ams(port)) {
+		port->vdm_state = VDM_STATE_ERR_BUSY;
+		tcpm_ams_finish(port);
+		mod_vdm_delayed_work(port, 0);
+	}
+
 	if (!(msg->ext_msg.header & PD_EXT_HDR_CHUNKED)) {
 		tcpm_pd_handle_msg(port, PD_MSG_CTRL_NOT_SUPP, NONE_AMS);
 		tcpm_log(port, "Unchunked extended messages unsupported");
-- 
2.31.1.818.g46aad6cb9e-goog