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Commit d854b01d authored by Jack Pham's avatar Jack Pham
Browse files

usb: pd: Avoid spurious state machine work on CC change 



If an unexpected or delayed Type-C mode change notification
arrives from the charger driver, it could falsely kick the
state machine and could cause it to prematurely hard reset
since it preempted an expected message. This is particularly
true for the PR Swap operation in which the timing of PS_RDY
and resulting power negotiation is disrupted by the CC change
notification which is catching up. The previous way of handling
this by using the pd->in_pr_swap flag to mask the typec_mode
changes is quite fragile due to the uncertainty of when said
flag should be cleared.

Hence, demote the use of the in_pr_swap flag for only ignoring
the expected disconnect the happens in between the role change.
Then, for typec_mode changes, determine if current_pr is changed
or not to decide whether to kick the state machine. Finally,
since disconnect now is signaled by pd->current_pr==PR_NONE,
we'll need to keep track of whether VBUS had been enabled with
a separate flag rather than relying on pd->current_pr==PR_SRC.

Change-Id: I66be40091b75726d25c7be4478f1248a6af9ca3c
Signed-off-by: default avatarJack Pham <jackp@codeaurora.org>
parent 019cc208

drivers/usb/pd/policy_engine.c

+45 −6
Original line number Diff line number Diff line
@@ -320,6 +320,7 @@ struct usbpd { 


	struct regulator	*vbus;

	struct regulator	*vconn;

	bool			vbus_enabled;

	bool			vconn_enabled;

	bool			vconn_is_external;
@@ -645,6 +646,7 @@ static void usbpd_set_state(struct usbpd *pd, enum usbpd_state next_state) 
	switch (next_state) {

	case PE_ERROR_RECOVERY: /* perform hard disconnect/reconnect */

		pd->in_pr_swap = false;

		pd->current_pr = PR_NONE;

		set_power_role(pd, PR_NONE);

		pd->typec_mode = POWER_SUPPLY_TYPEC_NONE;

		kick_sm(pd, 0);
@@ -691,6 +693,7 @@ static void usbpd_set_state(struct usbpd *pd, enum usbpd_state next_state) 
		pd->current_state = PE_SRC_SEND_CAPABILITIES;

		if (pd->in_pr_swap) {

			kick_sm(pd, SWAP_SOURCE_START_TIME);

			pd->in_pr_swap = false;

			break;

		}
@@ -1381,7 +1384,7 @@ static void usbpd_sm(struct work_struct *w) 
	spin_unlock_irqrestore(&pd->rx_lock, flags);



	/* Disconnect? */

	if (pd->typec_mode == POWER_SUPPLY_TYPEC_NONE && !pd->in_pr_swap) {

	if (pd->current_pr == PR_NONE) {

		if (pd->current_state == PE_UNKNOWN)

			goto sm_done;
@@ -1415,8 +1418,10 @@ static void usbpd_sm(struct work_struct *w) 
		power_supply_set_property(pd->usb_psy,

				POWER_SUPPLY_PROP_PD_ACTIVE, &val);



		if (pd->current_pr == PR_SRC)

		if (pd->vbus_enabled) {

			regulator_disable(pd->vbus);

			pd->vbus_enabled = false;

		}



		if (pd->vconn_enabled) {

			regulator_disable(pd->vconn);
@@ -1488,6 +1493,8 @@ static void usbpd_sm(struct work_struct *w) 
			ret = regulator_enable(pd->vbus);

			if (ret)

				usbpd_err(&pd->dev, "Unable to enable vbus\n");

			else

				pd->vbus_enabled = true;



			if (!pd->vconn_enabled &&

					pd->typec_mode ==
@@ -1633,6 +1640,7 @@ static void usbpd_sm(struct work_struct *w) 
	case PE_SRC_TRANSITION_TO_DEFAULT:

		if (pd->vconn_enabled)

			regulator_disable(pd->vconn);

		if (pd->vbus_enabled)

			regulator_disable(pd->vbus);



		if (pd->current_dr != DR_DFP) {
@@ -1643,9 +1651,12 @@ static void usbpd_sm(struct work_struct *w) 


		msleep(SRC_RECOVER_TIME);



		pd->vbus_enabled = false;

		ret = regulator_enable(pd->vbus);

		if (ret)

			usbpd_err(&pd->dev, "Unable to enable vbus\n");

		else

			pd->vbus_enabled = true;



		if (pd->vconn_enabled) {

			ret = regulator_enable(pd->vconn);
@@ -1685,11 +1696,27 @@ static void usbpd_sm(struct work_struct *w) 
			if (pd->vbus_present)

				usbpd_set_state(pd,

						PE_SNK_WAIT_FOR_CAPABILITIES);



			/*

			 * Handle disconnection in the middle of PR_Swap.

			 * Since in psy_changed() if pd->in_pr_swap is true

			 * we ignore the typec_mode==NONE change since that is

			 * expected to happen. However if the cable really did

			 * get disconnected we need to check for it here after

			 * waiting for VBUS presence times out.

			 */

			if (!pd->typec_mode) {

				pd->current_pr = PR_NONE;

				kick_sm(pd, 0);

			}



			break;

		}

		/* else fall-through */



	case PE_SNK_WAIT_FOR_CAPABILITIES:

		pd->in_pr_swap = false;



		if (IS_DATA(rx_msg, MSG_SOURCE_CAPABILITIES)) {

			val.intval = 0;

			power_supply_set_property(pd->usb_psy,
@@ -1977,7 +2004,10 @@ static void usbpd_sm(struct work_struct *w) 
		pd->in_pr_swap = true;

		pd->in_explicit_contract = false;



		if (pd->vbus_enabled) {

			regulator_disable(pd->vbus);

			pd->vbus_enabled = false;

		}



		/* PE_PRS_SRC_SNK_Assert_Rd */

		pd->current_pr = PR_SINK;
@@ -2032,6 +2062,8 @@ static void usbpd_sm(struct work_struct *w) 
		ret = regulator_enable(pd->vbus);

		if (ret)

			usbpd_err(&pd->dev, "Unable to enable vbus\n");

		else

			pd->vbus_enabled = true;



		msleep(200); /* allow time VBUS ramp-up, must be < tNewSrc */
@@ -2174,6 +2206,7 @@ static int psy_changed(struct notifier_block *nb, unsigned long evt, void *ptr) 
			return 0;

		}



		pd->current_pr = PR_NONE;

		break;



	/* Sink states */
@@ -2182,8 +2215,11 @@ static int psy_changed(struct notifier_block *nb, unsigned long evt, void *ptr) 
	case POWER_SUPPLY_TYPEC_SOURCE_HIGH:

		usbpd_info(&pd->dev, "Type-C Source (%s) connected\n",

				src_current(typec_mode));



		if (pd->current_pr == PR_SINK)

			return 0;



		pd->current_pr = PR_SINK;

		pd->in_pr_swap = false;

		break;



	/* Source states */
@@ -2192,8 +2228,11 @@ static int psy_changed(struct notifier_block *nb, unsigned long evt, void *ptr) 
		usbpd_info(&pd->dev, "Type-C Sink%s connected\n",

				typec_mode == POWER_SUPPLY_TYPEC_SINK ?

					"" : " (powered)");



		if (pd->current_pr == PR_SRC)

			return 0;



		pd->current_pr = PR_SRC;

		pd->in_pr_swap = false;

		break;



	case POWER_SUPPLY_TYPEC_SINK_DEBUG_ACCESSORY: