usb: pd: Support revision 3.0 in sink-only mode

commit 07040df2790e ("usb: pd: policy_engine: Handle spec revision
properly") changed the spec revision handling to be 2.0 mode unless
a programmable power supply is seen. Extend this via a module
parameter to allow PD 3.0 in sink-only mode regardless of PPS when
a 3.0 source is connected.

Since the revision of the source is first encountered when
receiving the Source Capabilities message, this information is
lost by the time pd_eval_src_caps() is called. So bring back the
handling in phy_msg_received() removed in commit 07040df2790e ("usb:
pd: policy_engine: Handle spec revision properly").

Change-Id: I0485224aeadcffbfaecd0c7942c6dbcd9ddd3813
Signed-off-by: Hemant Kumar <hemantk@codeaurora.org>

1 files changed, 27 insertions, 7 deletions

diff --git a/drivers/usb/pd/policy_engine.c b/drivers/usb/pd/policy_engine.c
index 77a1627ac5f2..f2383b62a68b 100644
--- a/drivers/usb/pd/policy_engine.c
+++ b/drivers/usb/pd/policy_engine.c
@@ -38,6 +38,10 @@ static bool disable_usb_pd;
 module_param(disable_usb_pd, bool, S_IRUGO|S_IWUSR);
 MODULE_PARM_DESC(disable_usb_pd, "Disable USB PD for USB3.1 compliance testing");
 
+static bool rev3_sink_only;
+module_param(rev3_sink_only, bool, 0644);
+MODULE_PARM_DESC(rev3_sink_only, "Enable power delivery rev3.0 sink only mode");
+
 enum usbpd_state {
 	PE_UNKNOWN,
 	PE_ERROR_RECOVERY,
@@ -670,7 +674,7 @@ static int pd_select_pdo(struct usbpd *pd, int pdo_pos, int uv, int ua)
 
 static int pd_eval_src_caps(struct usbpd *pd)
 {
-	int obj_cnt;
+	int i;
 	union power_supply_propval val;
 	u32 first_pdo = pd->received_pdos[0];
 
@@ -687,11 +691,20 @@ static int pd_eval_src_caps(struct usbpd *pd)
 	power_supply_set_property(pd->usb_psy,
 			POWER_SUPPLY_PROP_PD_USB_SUSPEND_SUPPORTED, &val);
 
-	for (obj_cnt = 1; obj_cnt < PD_MAX_DATA_OBJ; obj_cnt++) {
-		if ((PD_SRC_PDO_TYPE(pd->received_pdos[obj_cnt]) ==
+	if (pd->spec_rev == USBPD_REV_30 && !rev3_sink_only) {
+		bool pps_found = false;
+
+		/* downgrade to 2.0 if no PPS */
+		for (i = 1; i < PD_MAX_DATA_OBJ; i++) {
+			if ((PD_SRC_PDO_TYPE(pd->received_pdos[i]) ==
 					PD_SRC_PDO_TYPE_AUGMENTED) &&
-				!PD_APDO_PPS(pd->received_pdos[obj_cnt]))
-			pd->spec_rev = USBPD_REV_30;
+				!PD_APDO_PPS(pd->received_pdos[i])) {
+				pps_found = true;
+				break;
+			}
+		}
+		if (!pps_found)
+			pd->spec_rev = USBPD_REV_20;
 	}
 
 	/* Select the first PDO (vSafe5V) immediately. */
@@ -1034,6 +1047,8 @@ static void usbpd_set_state(struct usbpd *pd, enum usbpd_state next_state)
 		power_supply_set_property(pd->usb_psy,
 				POWER_SUPPLY_PROP_TYPEC_POWER_ROLE, &val);
 
+		/* support only PD 2.0 as a source */
+		pd->spec_rev = USBPD_REV_20;
 		pd_reset_protocol(pd);
 
 		if (!pd->in_pr_swap) {
@@ -1204,6 +1219,11 @@ static void usbpd_set_state(struct usbpd *pd, enum usbpd_state next_state)
 		if (!val.intval || disable_usb_pd)
 			break;
 
+		/*
+		 * support up to PD 3.0 as a sink; if source is 2.0
+		 * phy_msg_received() will handle the downgrade.
+		 */
+		pd->spec_rev = USBPD_REV_30;
 		pd_reset_protocol(pd);
 
 		if (!pd->in_pr_swap) {
@@ -1909,6 +1929,8 @@ static void usbpd_sm(struct work_struct *w)
 		/* set due to dual_role class "mode" change */
 		if (pd->forced_pr != POWER_SUPPLY_TYPEC_PR_NONE)
 			val.intval = pd->forced_pr;
+		else if (rev3_sink_only)
+			val.intval = POWER_SUPPLY_TYPEC_PR_SINK;
 		else
 			/* Set CC back to DRP toggle */
 			val.intval = POWER_SUPPLY_TYPEC_PR_DUAL;
@@ -3910,8 +3932,6 @@ struct usbpd *usbpd_create(struct device *parent)
 		pd->dual_role->drv_data = pd;
 	}
 
-	/* default support as PD 2.0 source or sink */
-	pd->spec_rev = USBPD_REV_20;
 	pd->current_pr = PR_NONE;
 	pd->current_dr = DR_NONE;
 	list_add_tail(&pd->instance, &_usbpd);