usb: typec: tcpm: Wait for vbus discharge to VSAFE0V before toggling

When vbus auto discharge is enabled, TCPM can sometimes be faster than the TCPC i.e. TCPM can go ahead and move the port to unattached state (involves disabling vbus auto discharge) before TCPC could effectively discharge vbus to VSAFE0V. This leaves vbus with residual charge and increases the decay time which prevents tsafe0v from being met. This change introduces a new state VBUS_DISCHARGE where the TCPM waits for a maximum of tSafe0V(max) for vbus to discharge to VSAFE0V before transitioning to unattached state and re-enable toggling. If vbus discharges to vsafe0v sooner, then, transition to unattached state happens right away.

Also, while in SNK_READY, when auto discharge is enabled, drive disconnect based on vbus turning off instead of Rp disappearing on CC pins. Rp disappearing on CC pins is almost instanteous compared to vbus decay.

Fixes f321a02caebd ("usb: typec: tcpm: Implement enabling Auto

Discharge disconnect support")

Signed-off-by Badhri Jagan Sridharan <[email protected]>

---
Changes since V1:
- Add Fixes tag

---
 drivers/usb/typec/tcpm/tcpm.c | 60 +++++++++++++++++++++++++++++++----
 1 file changed, 53 insertions(+), 7 deletions(-)

drivers/usb/typec/tcpm/tcpm.c +17 -0

index be0b6469dd3d..0ed71725980f 100644
@@ -62,6 +62,8 @@
 	S(SNK_TRANSITION_SINK_VBUS),		\
 	S(SNK_READY),				\
 						\
+	S(VBUS_DISCHARGE),			\
+						\
 	S(ACC_UNATTACHED),			\
 	S(DEBUG_ACC_ATTACHED),			\
 	S(AUDIO_ACC_ATTACHED),			\

@@ -438,6 +440,9 @@ struct tcpm_port {
 	enum tcpm_ams next_ams;
 	bool in_ams;
 
+	/* Auto vbus discharge state */
+	bool auto_vbus_discharge_enabled;
+
 #ifdef CONFIG_DEBUG_FS
 	struct dentry *dentry;
 	struct mutex logbuffer_lock;	/* log buffer access lock */

@@ -3413,6 +3418,8 @@ static int tcpm_src_attach(struct tcpm_port *port)
 	if (port->tcpc->enable_auto_vbus_discharge) {
 		ret = port->tcpc->enable_auto_vbus_discharge(port->tcpc, true);
 		tcpm_log_force(port, "enable vbus discharge ret:%d", ret);
+		if (!ret)
+			port->auto_vbus_discharge_enabled = true;
 	}
 
 	ret = tcpm_set_roles(port, true, TYPEC_SOURCE, tcpm_data_role_for_source(port));

@@ -3495,6 +3502,8 @@ static void tcpm_reset_port(struct tcpm_port *port)
 	if (port->tcpc->enable_auto_vbus_discharge) {
 		ret = port->tcpc->enable_auto_vbus_discharge(port->tcpc, false);
 		tcpm_log_force(port, "Disable vbus discharge ret:%d", ret);
+		if (!ret)
+			port->auto_vbus_discharge_enabled = false;
 	}
 	port->in_ams = false;
 	port->ams = NONE_AMS;

@@ -3568,6 +3577,8 @@ static int tcpm_snk_attach(struct tcpm_port *port)
 		tcpm_set_auto_vbus_discharge_threshold(port, TYPEC_PWR_MODE_USB, false, VSAFE5V);
 		ret = port->tcpc->enable_auto_vbus_discharge(port->tcpc, true);
 		tcpm_log_force(port, "enable vbus discharge ret:%d", ret);
+		if (!ret)
+			port->auto_vbus_discharge_enabled = true;
 	}
 
 	ret = tcpm_set_roles(port, true, TYPEC_SINK, tcpm_data_role_for_sink(port));

@@ -3684,6 +3695,12 @@ static void run_state_machine(struct tcpm_port *port)
 	switch (port->state) {
 	case TOGGLING:
 		break;
+	case VBUS_DISCHARGE:
+		if (port->port_type == TYPEC_PORT_SRC)
+			tcpm_set_state(port, SRC_UNATTACHED, PD_T_SAFE_0V);
+		else
+			tcpm_set_state(port, SNK_UNATTACHED, PD_T_SAFE_0V);
+		break;
 	/* SRC states */
 	case SRC_UNATTACHED:
 		if (!port->non_pd_role_swap)

drivers/usb/typec/tcpm/tcpm.c +33 -6

@@ -4703,7 +4722,18 @@ static void _tcpm_cc_change(struct tcpm_port *port, enum typec_cc_status cc1,
 			tcpm_set_state(port, SNK_DEBOUNCED, 0);
 		break;
 	case SNK_READY:
-		if (tcpm_port_is_disconnected(port))
+		/*
+		 * When set_auto_vbus_discharge_threshold is enabled, CC pins go
+		 * away before vbus decays to disconnect threshold. Allow
+		 * disconnect to be driven by vbus disconnect when auto vbus
+		 * discharge is enabled.
+		 *
+		 * EXIT condition is based primarily on vbus disconnect and CC is secondary.
+		 * "A port that has entered into USB PD communications with the Source and
+		 * has seen the CC voltage exceed vRd-USB may monitor the CC pin to detect
+		 * cable disconnect in addition to monitoring VBUS.
+		 */
+		if (!port->auto_vbus_discharge_enabled && tcpm_port_is_disconnected(port))
 			tcpm_set_state(port, unattached_state(port), 0);
 		else if (!port->pd_capable &&
 			 (cc1 != old_cc1 || cc2 != old_cc2))

@@ -4803,9 +4833,16 @@ static void _tcpm_cc_change(struct tcpm_port *port, enum typec_cc_status cc1,
 		 */
 		break;
 
+	case VBUS_DISCHARGE:
+		/* Do nothing. Waiting for vsafe0v signal */
+		break;
 	default:
-		if (tcpm_port_is_disconnected(port))
-			tcpm_set_state(port, unattached_state(port), 0);
+		if (tcpm_port_is_disconnected(port)) {
+			if (port->auto_vbus_discharge_enabled && !port->vbus_vsafe0v)
+				tcpm_set_state(port, VBUS_DISCHARGE, 0);
+			else
+				tcpm_set_state(port, unattached_state(port), 0);
+		}
 		break;
 	}
 }

@@ -4988,9 +5025,12 @@ static void _tcpm_pd_vbus_off(struct tcpm_port *port)
 		break;
 
 	default:
-		if (port->pwr_role == TYPEC_SINK &&
-		    port->attached)
-			tcpm_set_state(port, SNK_UNATTACHED, 0);
+		if (port->pwr_role == TYPEC_SINK && port->attached) {
+			if (port->auto_vbus_discharge_enabled && !port->vbus_vsafe0v)
+				tcpm_set_state(port, VBUS_DISCHARGE, 0);
+			else
+				tcpm_set_state(port, SNK_UNATTACHED, 0);
+		}
 		break;
 	}
 }

@@ -5012,6 +5052,12 @@ static void _tcpm_pd_vbus_vsafe0v(struct tcpm_port *port)
 			tcpm_set_state(port, tcpm_try_snk(port) ? SNK_TRY : SRC_ATTACHED,
 				       PD_T_CC_DEBOUNCE);
 		break;
+	case VBUS_DISCHARGE:
+		if (port->port_type == TYPEC_PORT_SRC)
+			tcpm_set_state(port, SRC_UNATTACHED, 0);
+		else
+			tcpm_set_state(port, SNK_UNATTACHED, 0);
+		break;
 	default:
 		break;
 	}

Quoted 90 lines · Badhri Jagan Sridharan

When vbus auto discharge is enabled, TCPM can sometimes be faster than the TCPC i.e. TCPM can go ahead and move the port to unattached state (involves disabling vbus auto discharge) before TCPC could effectively discharge vbus to VSAFE0V. This leaves vbus with residual charge and increases the decay time which prevents tsafe0v from being met. This change introduces a new state VBUS_DISCHARGE where the TCPM waits for a maximum of tSafe0V(max) for vbus to discharge to VSAFE0V before transitioning to unattached state and re-enable toggling. If vbus discharges to vsafe0v sooner, then, transition to unattached state happens right away.

Also, while in SNK_READY, when auto discharge is enabled, drive disconnect based on vbus turning off instead of Rp disappearing on CC pins. Rp disappearing on CC pins is almost instanteous compared to vbus decay.

Fixes f321a02caebd ("usb: typec: tcpm: Implement enabling Auto

Discharge disconnect support")

Signed-off-by Badhri Jagan Sridharan <[email protected]>

---
Changes since V1:
- Add Fixes tag

---
 drivers/usb/typec/tcpm/tcpm.c | 60 +++++++++++++++++++++++++++++++----
 1 file changed, 53 insertions(+), 7 deletions(-)

drivers/usb/typec/tcpm/tcpm.c +17 -0

index be0b6469dd3d..0ed71725980f 100644
@@ -62,6 +62,8 @@
      S(SNK_TRANSITION_SINK_VBUS),            \
      S(SNK_READY),                           \
                                              \
+     S(VBUS_DISCHARGE),                      \
+                                             \
      S(ACC_UNATTACHED),                      \
      S(DEBUG_ACC_ATTACHED),                  \
      S(AUDIO_ACC_ATTACHED),                  \

@@ -438,6 +440,9 @@ struct tcpm_port {
      enum tcpm_ams next_ams;
      bool in_ams;
 
+     /* Auto vbus discharge state */
+     bool auto_vbus_discharge_enabled;
+
 #ifdef CONFIG_DEBUG_FS
      struct dentry *dentry;
      struct mutex logbuffer_lock;    /* log buffer access lock */

@@ -3413,6 +3418,8 @@ static int tcpm_src_attach(struct tcpm_port *port)
      if (port->tcpc->enable_auto_vbus_discharge) {
              ret = port->tcpc->enable_auto_vbus_discharge(port->tcpc, true);
              tcpm_log_force(port, "enable vbus discharge ret:%d", ret);
+             if (!ret)
+                     port->auto_vbus_discharge_enabled = true;
      }
 
      ret = tcpm_set_roles(port, true, TYPEC_SOURCE, tcpm_data_role_for_source(port));

@@ -3495,6 +3502,8 @@ static void tcpm_reset_port(struct tcpm_port *port)
      if (port->tcpc->enable_auto_vbus_discharge) {
              ret = port->tcpc->enable_auto_vbus_discharge(port->tcpc, false);
              tcpm_log_force(port, "Disable vbus discharge ret:%d", ret);
+             if (!ret)
+                     port->auto_vbus_discharge_enabled = false;
      }
      port->in_ams = false;
      port->ams = NONE_AMS;

@@ -3568,6 +3577,8 @@ static int tcpm_snk_attach(struct tcpm_port *port)
              tcpm_set_auto_vbus_discharge_threshold(port, TYPEC_PWR_MODE_USB, false, VSAFE5V);
              ret = port->tcpc->enable_auto_vbus_discharge(port->tcpc, true);
              tcpm_log_force(port, "enable vbus discharge ret:%d", ret);
+             if (!ret)
+                     port->auto_vbus_discharge_enabled = true;
      }
 
      ret = tcpm_set_roles(port, true, TYPEC_SINK, tcpm_data_role_for_sink(port));

@@ -3684,6 +3695,12 @@ static void run_state_machine(struct tcpm_port *port)
      switch (port->state) {
      case TOGGLING:
              break;
+     case VBUS_DISCHARGE:
+             if (port->port_type == TYPEC_PORT_SRC)
+                     tcpm_set_state(port, SRC_UNATTACHED, PD_T_SAFE_0V);
+             else
+                     tcpm_set_state(port, SNK_UNATTACHED, PD_T_SAFE_0V);
+             break;
      /* SRC states */
      case SRC_UNATTACHED:
              if (!port->non_pd_role_swap)

drivers/usb/typec/tcpm/tcpm.c static void _tcpm_cc_change(struct tcpm_port *port, enum typec_cc_status cc1, · line 4694

Quoted 10 lines

drivers/usb/typec/tcpm/tcpm.c +3 -1

@@ -4669,7 +4686,9 @@ static void _tcpm_cc_change(struct tcpm_port *port, enum typec_cc_status cc1,
      case SRC_READY:
              if (tcpm_port_is_disconnected(port) ||
                  !tcpm_port_is_source(port)) {
-                     if (port->port_type == TYPEC_PORT_SRC)
+                     if (port->auto_vbus_discharge_enabled && !port->vbus_vsafe0v)
+                             tcpm_set_state(port, VBUS_DISCHARGE, 0);
+                     else if (port->port_type == TYPEC_PORT_SRC)
                              tcpm_set_state(port, SRC_UNATTACHED, 0);
                      else
                              tcpm_set_state(port, SNK_UNATTACHED, 0);

Unless I am missing something, the new state is only used to set the PD_T_SAFE_0V timeout. Is it really necessary/useful to add a new state just for that, while keeping the rest of if/else statements ? Personally I would prefer something like

                        timeout = (port->auto_vbus_discharge_enabled && !port->vbus_vsafe0v) ? PD_T_SAFE_0V : 0;
                        if (port->port_type == TYPEC_PORT_SRC)
                                tcpm_set_state(port, SRC_UNATTACHED, timeout);
                        else
                                tcpm_set_state(port, SNK_UNATTACHED, timeout);

In this context, any idea why port_type==TYPEC_PORT_DRP results in SNK_UNATTACHED state ? That seems a bit odd.

Guenter

Quoted 69 lines

drivers/usb/typec/tcpm/tcpm.c +33 -6

@@ -4703,7 +4722,18 @@ static void _tcpm_cc_change(struct tcpm_port *port, enum typec_cc_status cc1,
                      tcpm_set_state(port, SNK_DEBOUNCED, 0);
              break;
      case SNK_READY:
-             if (tcpm_port_is_disconnected(port))
+             /*
+              * When set_auto_vbus_discharge_threshold is enabled, CC pins go
+              * away before vbus decays to disconnect threshold. Allow
+              * disconnect to be driven by vbus disconnect when auto vbus
+              * discharge is enabled.
+              *
+              * EXIT condition is based primarily on vbus disconnect and CC is secondary.
+              * "A port that has entered into USB PD communications with the Source and
+              * has seen the CC voltage exceed vRd-USB may monitor the CC pin to detect
+              * cable disconnect in addition to monitoring VBUS.
+              */
+             if (!port->auto_vbus_discharge_enabled && tcpm_port_is_disconnected(port))
                      tcpm_set_state(port, unattached_state(port), 0);
              else if (!port->pd_capable &&
                       (cc1 != old_cc1 || cc2 != old_cc2))

@@ -4803,9 +4833,16 @@ static void _tcpm_cc_change(struct tcpm_port *port, enum typec_cc_status cc1,
               */
              break;
 
+     case VBUS_DISCHARGE:
+             /* Do nothing. Waiting for vsafe0v signal */
+             break;
      default:
-             if (tcpm_port_is_disconnected(port))
-                     tcpm_set_state(port, unattached_state(port), 0);
+             if (tcpm_port_is_disconnected(port)) {
+                     if (port->auto_vbus_discharge_enabled && !port->vbus_vsafe0v)
+                             tcpm_set_state(port, VBUS_DISCHARGE, 0);
+                     else
+                             tcpm_set_state(port, unattached_state(port), 0);
+             }
              break;
      }
 }

@@ -4988,9 +5025,12 @@ static void _tcpm_pd_vbus_off(struct tcpm_port *port)
              break;
 
      default:
-             if (port->pwr_role == TYPEC_SINK &&
-                 port->attached)
-                     tcpm_set_state(port, SNK_UNATTACHED, 0);
+             if (port->pwr_role == TYPEC_SINK && port->attached) {
+                     if (port->auto_vbus_discharge_enabled && !port->vbus_vsafe0v)
+                             tcpm_set_state(port, VBUS_DISCHARGE, 0);
+                     else
+                             tcpm_set_state(port, SNK_UNATTACHED, 0);
+             }
              break;
      }
 }

@@ -5012,6 +5052,12 @@ static void _tcpm_pd_vbus_vsafe0v(struct tcpm_port *port)
                      tcpm_set_state(port, tcpm_try_snk(port) ? SNK_TRY : SRC_ATTACHED,
                                     PD_T_CC_DEBOUNCE);
              break;
+     case VBUS_DISCHARGE:
+             if (port->port_type == TYPEC_PORT_SRC)
+                     tcpm_set_state(port, SRC_UNATTACHED, 0);
+             else
+                     tcpm_set_state(port, SNK_UNATTACHED, 0);
+             break;
      default:
              break;
      }

Quoted 107 lines · Guenter Roeck

Quoted 90 lines · Badhri Jagan Sridharan

When vbus auto discharge is enabled, TCPM can sometimes be faster than the TCPC i.e. TCPM can go ahead and move the port to unattached state (involves disabling vbus auto discharge) before TCPC could effectively discharge vbus to VSAFE0V. This leaves vbus with residual charge and increases the decay time which prevents tsafe0v from being met. This change introduces a new state VBUS_DISCHARGE where the TCPM waits for a maximum of tSafe0V(max) for vbus to discharge to VSAFE0V before transitioning to unattached state and re-enable toggling. If vbus discharges to vsafe0v sooner, then, transition to unattached state happens right away.

Also, while in SNK_READY, when auto discharge is enabled, drive disconnect based on vbus turning off instead of Rp disappearing on CC pins. Rp disappearing on CC pins is almost instanteous compared to vbus decay.

Fixes f321a02caebd ("usb: typec: tcpm: Implement enabling Auto

Discharge disconnect support")

Signed-off-by Badhri Jagan Sridharan <[email protected]>

---
Changes since V1:
- Add Fixes tag

---
 drivers/usb/typec/tcpm/tcpm.c | 60 +++++++++++++++++++++++++++++++----
 1 file changed, 53 insertions(+), 7 deletions(-)

drivers/usb/typec/tcpm/tcpm.c +17 -0

index be0b6469dd3d..0ed71725980f 100644
@@ -62,6 +62,8 @@
      S(SNK_TRANSITION_SINK_VBUS),            \
      S(SNK_READY),                           \
                                              \
+     S(VBUS_DISCHARGE),                      \
+                                             \
      S(ACC_UNATTACHED),                      \
      S(DEBUG_ACC_ATTACHED),                  \
      S(AUDIO_ACC_ATTACHED),                  \

@@ -438,6 +440,9 @@ struct tcpm_port {
      enum tcpm_ams next_ams;
      bool in_ams;
 
+     /* Auto vbus discharge state */
+     bool auto_vbus_discharge_enabled;
+
 #ifdef CONFIG_DEBUG_FS
      struct dentry *dentry;
      struct mutex logbuffer_lock;    /* log buffer access lock */

@@ -3413,6 +3418,8 @@ static int tcpm_src_attach(struct tcpm_port *port)
      if (port->tcpc->enable_auto_vbus_discharge) {
              ret = port->tcpc->enable_auto_vbus_discharge(port->tcpc, true);
              tcpm_log_force(port, "enable vbus discharge ret:%d", ret);
+             if (!ret)
+                     port->auto_vbus_discharge_enabled = true;
      }
 
      ret = tcpm_set_roles(port, true, TYPEC_SOURCE, tcpm_data_role_for_source(port));

@@ -3495,6 +3502,8 @@ static void tcpm_reset_port(struct tcpm_port *port)
      if (port->tcpc->enable_auto_vbus_discharge) {
              ret = port->tcpc->enable_auto_vbus_discharge(port->tcpc, false);
              tcpm_log_force(port, "Disable vbus discharge ret:%d", ret);
+             if (!ret)
+                     port->auto_vbus_discharge_enabled = false;
      }
      port->in_ams = false;
      port->ams = NONE_AMS;

@@ -3568,6 +3577,8 @@ static int tcpm_snk_attach(struct tcpm_port *port)
              tcpm_set_auto_vbus_discharge_threshold(port, TYPEC_PWR_MODE_USB, false, VSAFE5V);
              ret = port->tcpc->enable_auto_vbus_discharge(port->tcpc, true);
              tcpm_log_force(port, "enable vbus discharge ret:%d", ret);
+             if (!ret)
+                     port->auto_vbus_discharge_enabled = true;
      }
 
      ret = tcpm_set_roles(port, true, TYPEC_SINK, tcpm_data_role_for_sink(port));

@@ -3684,6 +3695,12 @@ static void run_state_machine(struct tcpm_port *port)
      switch (port->state) {
      case TOGGLING:
              break;
+     case VBUS_DISCHARGE:
+             if (port->port_type == TYPEC_PORT_SRC)
+                     tcpm_set_state(port, SRC_UNATTACHED, PD_T_SAFE_0V);
+             else
+                     tcpm_set_state(port, SNK_UNATTACHED, PD_T_SAFE_0V);
+             break;
      /* SRC states */
      case SRC_UNATTACHED:
              if (!port->non_pd_role_swap)

drivers/usb/typec/tcpm/tcpm.c static void _tcpm_cc_change(struct tcpm_port *port, enum typec_cc_status cc1, · line 4694

Quoted 10 lines

drivers/usb/typec/tcpm/tcpm.c +3 -1

@@ -4669,7 +4686,9 @@ static void _tcpm_cc_change(struct tcpm_port *port, enum typec_cc_status cc1,
      case SRC_READY:
              if (tcpm_port_is_disconnected(port) ||
                  !tcpm_port_is_source(port)) {
-                     if (port->port_type == TYPEC_PORT_SRC)
+                     if (port->auto_vbus_discharge_enabled && !port->vbus_vsafe0v)
+                             tcpm_set_state(port, VBUS_DISCHARGE, 0);
+                     else if (port->port_type == TYPEC_PORT_SRC)
                              tcpm_set_state(port, SRC_UNATTACHED, 0);
                      else
                              tcpm_set_state(port, SNK_UNATTACHED, 0);

Unless I am missing something, the new state is only used to set the PD_T_SAFE_0V timeout. Is it really necessary/useful to add a new state just for that, while keeping the rest of if/else statements ? Personally I would prefer something like

Quoted 6 lines

                        timeout = (port->auto_vbus_discharge_enabled && !port->vbus_vsafe0v) ? PD_T_SAFE_0V : 0;
                        if (port->port_type == TYPEC_PORT_SRC)
                                tcpm_set_state(port, SRC_UNATTACHED, timeout);
                        else
                                tcpm_set_state(port, SNK_UNATTACHED, timeout);

Yes this should be OK as well. I was thinking it would be more clearer during debug if there
was a separate state altogether, but, looks like we should be fine. Implementing/Validating it now. Will send a follow up version today.

Quoted 3 lines

In this context, any idea why port_type==TYPEC_PORT_DRP results in SNK_UNATTACHED state ? That seems a bit odd.

This comes from the patch here:
https://lore.kernel.org/r/[email protected]

Looks reasonable to me as tcpm_*_detach functions call tcpm_detach so teardown should
happen anyways.

static void tcpm_snk_detach(struct tcpm_port *port)

{
        tcpm_detach(port);
}

static void tcpm_src_detach(struct tcpm_port *port)

{
        tcpm_detach(port);
}

Thanks,
Badhri

Quoted 73 lines

Guenter

Quoted 69 lines

drivers/usb/typec/tcpm/tcpm.c +33 -6

@@ -4703,7 +4722,18 @@ static void _tcpm_cc_change(struct tcpm_port *port, enum typec_cc_status cc1,
                      tcpm_set_state(port, SNK_DEBOUNCED, 0);
              break;
      case SNK_READY:
-             if (tcpm_port_is_disconnected(port))
+             /*
+              * When set_auto_vbus_discharge_threshold is enabled, CC pins go
+              * away before vbus decays to disconnect threshold. Allow
+              * disconnect to be driven by vbus disconnect when auto vbus
+              * discharge is enabled.
+              *
+              * EXIT condition is based primarily on vbus disconnect and CC is secondary.
+              * "A port that has entered into USB PD communications with the Source and
+              * has seen the CC voltage exceed vRd-USB may monitor the CC pin to detect
+              * cable disconnect in addition to monitoring VBUS.
+              */
+             if (!port->auto_vbus_discharge_enabled && tcpm_port_is_disconnected(port))
                      tcpm_set_state(port, unattached_state(port), 0);
              else if (!port->pd_capable &&
                       (cc1 != old_cc1 || cc2 != old_cc2))

@@ -4803,9 +4833,16 @@ static void _tcpm_cc_change(struct tcpm_port *port, enum typec_cc_status cc1,
               */
              break;
 
+     case VBUS_DISCHARGE:
+             /* Do nothing. Waiting for vsafe0v signal */
+             break;
      default:
-             if (tcpm_port_is_disconnected(port))
-                     tcpm_set_state(port, unattached_state(port), 0);
+             if (tcpm_port_is_disconnected(port)) {
+                     if (port->auto_vbus_discharge_enabled && !port->vbus_vsafe0v)
+                             tcpm_set_state(port, VBUS_DISCHARGE, 0);
+                     else
+                             tcpm_set_state(port, unattached_state(port), 0);
+             }
              break;
      }
 }

@@ -4988,9 +5025,12 @@ static void _tcpm_pd_vbus_off(struct tcpm_port *port)
              break;
 
      default:
-             if (port->pwr_role == TYPEC_SINK &&
-                 port->attached)
-                     tcpm_set_state(port, SNK_UNATTACHED, 0);
+             if (port->pwr_role == TYPEC_SINK && port->attached) {
+                     if (port->auto_vbus_discharge_enabled && !port->vbus_vsafe0v)
+                             tcpm_set_state(port, VBUS_DISCHARGE, 0);
+                     else
+                             tcpm_set_state(port, SNK_UNATTACHED, 0);
+             }
              break;
      }
 }

@@ -5012,6 +5052,12 @@ static void _tcpm_pd_vbus_vsafe0v(struct tcpm_port *port)
                      tcpm_set_state(port, tcpm_try_snk(port) ? SNK_TRY : SRC_ATTACHED,
                                     PD_T_CC_DEBOUNCE);
              break;
+     case VBUS_DISCHARGE:
+             if (port->port_type == TYPEC_PORT_SRC)
+                     tcpm_set_state(port, SRC_UNATTACHED, 0);
+             else
+                     tcpm_set_state(port, SNK_UNATTACHED, 0);
+             break;
      default:
              break;
      }