usb_pd: USB4: Limit the cable speed

Added 'get_usb4_cable_speed()' to return USB4 speed as per the port, the
speed supported by DUT's port or cable speed whichever is lowest.

Added configuring the cable speed in cros_ec_usb_pd_control according to
the mux setting.

Removed 'set_max_usb4_cable_speed()' to retain cable's actual VDO
response.

BUG=b:157671582
BRANCH=none
TEST=1. Able to set USB4/USB3.2 Gen2 cable speed when DFP isn't gen 3
         capable.
     2. Able to limit cable speed according to the port, if the cable
        speed is higher.

Signed-off-by: Ayushee <ayushee.shah@intel.com>
Change-Id: I21bba7e5a2aa8ca54f304ef8418320f319f020b1
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/ec/+/2220826
Reviewed-by: Keith Short <keithshort@chromium.org>

3 files changed, 43 insertions, 37 deletions

diff --git a/common/usb_pd_alt_mode_dfp.c b/common/usb_pd_alt_mode_dfp.c
index 051fa9740c..42b21a6fa8 100644
--- a/common/usb_pd_alt_mode_dfp.c
+++ b/common/usb_pd_alt_mode_dfp.c
@@ -881,27 +881,47 @@ __overridable enum tbt_compat_cable_speed board_get_max_tbt_speed(int port)
  * ############################################################################
  */
 
-enum usb_rev30_ss get_usb4_cable_speed(int port)
+/*
+ * For Cable rev 3.0: USB4 cable speed is set according to speed supported by
+ * the port and the response received from the cable, whichever is least.
+ *
+ * For Cable rev 2.0: Since board_is_tbt_usb4_port() should not enabled if the
+ * port supports speed less than USB_R20_SS_U31_GEN1_GEN2, USB4 cable speed is
+ * set according to the cable response.
+ */
+static enum usb_rev30_ss board_get_max_usb_cable_speed(int port)
 {
 	struct pd_cable *cable = pd_get_cable_attributes(port);
-
 	/*
-	 * TODO: Return USB4 cable speed for USB3.2 Gen 2 cables if DFP isn't
-	 * Gen 3 capable.
+	 * Converting Thunderbolt-Compatible board speed to equivalent USB4
+	 * speed.
 	 */
-	if ((cable->rev == PD_REV30) &&
-	    (get_usb_pd_cable_type(port) == IDH_PTYPE_PCABLE) &&
-	   ((cable->attr.p_rev30.ss != USB_R30_SS_U32_U40_GEN2) ||
-	    !IS_ENABLED(CONFIG_USB_PD_TBT_GEN3_CAPABLE))) {
-		return cable->attr.p_rev30.ss;
-	}
+	enum usb_rev30_ss max_usb4_speed =
+		board_get_max_tbt_speed(port) == TBT_SS_TBT_GEN3 ?
+		USB_R30_SS_U40_GEN3 : USB_R30_SS_U32_U40_GEN2;
 
+	return max_usb4_speed < cable->attr.p_rev30.ss ?
+	       max_usb4_speed : cable->attr.p_rev30.ss;
+}
+
+enum usb_rev30_ss get_usb4_cable_speed(int port)
+{
+	struct pd_cable *cable = pd_get_cable_attributes(port);
+	enum usb_rev30_ss max_rev30_usb4_speed;
+
+	if (cable->rev == PD_REV30) {
+		max_rev30_usb4_speed = board_get_max_usb_cable_speed(port);
+		if (!IS_ENABLED(CONFIG_USB_PD_TBT_GEN3_CAPABLE) ||
+		     max_rev30_usb4_speed != USB_R30_SS_U32_U40_GEN2 ||
+		     get_usb_pd_cable_type(port) == IDH_PTYPE_ACABLE)
+			return max_rev30_usb4_speed;
+	}
 	/*
 	 * Converting Thunderolt-Compatible cable speed to equivalent USB4 cable
 	 * speed.
 	 */
-	return cable->cable_mode_resp.tbt_cable_speed == TBT_SS_TBT_GEN3 ?
-	       USB_R30_SS_U40_GEN3 : USB_R30_SS_U32_U40_GEN2;
+	return get_tbt_cable_speed(port) == TBT_SS_TBT_GEN3 ?
+		USB_R30_SS_U40_GEN3 : USB_R30_SS_U32_U40_GEN2;
 }
 
 __overridable void svdm_safe_dp_mode(int port)
diff --git a/common/usb_pd_host_cmd.c b/common/usb_pd_host_cmd.c
index 11345a7624..8bd9f16aea 100644
--- a/common/usb_pd_host_cmd.c
+++ b/common/usb_pd_host_cmd.c
@@ -296,6 +296,7 @@ static enum ec_status hc_usb_pd_control(struct host_cmd_handler_args *args)
 	struct ec_response_usb_pd_control_v1 *r_v1 = args->response;
 	struct ec_response_usb_pd_control *r = args->response;
 	const char *task_state_name;
+	mux_state_t mux_state;
 
 	if (p->port >= board_get_usb_pd_port_count())
 		return EC_RES_INVALID_PARAM;
@@ -360,8 +361,16 @@ static enum ec_status hc_usb_pd_control(struct host_cmd_handler_args *args)
 		r_v2->control_flags = get_pd_control_flags(p->port);
 		if (IS_ENABLED(CONFIG_USB_PD_ALT_MODE_DFP)) {
 			r_v2->dp_mode = get_dp_pin_mode(p->port);
-			r_v2->cable_speed = get_tbt_cable_speed(p->port);
-			r_v2->cable_gen = get_tbt_rounded_support(p->port);
+			mux_state = usb_mux_get(p->port);
+			if (mux_state & USB_PD_MUX_USB4_ENABLED) {
+				r_v2->cable_speed =
+					get_usb4_cable_speed(p->port);
+			} else if (mux_state & USB_PD_MUX_TBT_COMPAT_ENABLED) {
+				r_v2->cable_speed =
+					get_tbt_cable_speed(p->port);
+				r_v2->cable_gen =
+					get_tbt_rounded_support(p->port);
+			}
 		}
 
 		if (args->version == 1)
diff --git a/common/usb_pd_policy.c b/common/usb_pd_policy.c
index 38bb04f83b..8a92ac879f 100644
--- a/common/usb_pd_policy.c
+++ b/common/usb_pd_policy.c
@@ -346,28 +346,6 @@ static inline void disable_usb4_mode(int port)
 }
 
 /*
- * For Cable rev 3.0: USB4 cable speed is set according to speed supported by
- * the port and the response received from the cable, whichever is least.
- *
- * For Cable rev 2.0: Since board_is_tbt_usb4_port() should not enabled if the
- * port supports speed less than USB_R20_SS_U31_GEN1_GEN2, USB4 cable speed is
- * set according to the cable response.
- */
-static void set_max_usb4_cable_speed(int port)
-{
-	/*
-	 * Converting Thunderbolt-Compatible board speed to equivalent USB4
-	 * speed.
-	 */
-	enum usb_rev30_ss max_usb4_speed =
-			board_get_max_tbt_speed(port) == TBT_SS_TBT_GEN3 ?
-			USB_R30_SS_U40_GEN3 : USB_R30_SS_U32_U40_GEN2;
-
-	if (max_usb4_speed < cable[port].attr.p_rev30.ss)
-		cable[port].attr.p_rev30.ss = max_usb4_speed;
-}
-
-/*
  * Ref: USB Type-C Cable and Connector Specification
  * Figure 5-1 USB4 Discovery and Entry Flow Model.
  *
@@ -410,7 +388,6 @@ static bool is_cable_ready_to_enter_usb4(int port, int cnt)
 	    is_vdo_present(cnt, VDO_INDEX_PTYPE_CABLE1)) {
 		switch (cable[port].rev) {
 		case PD_REV30:
-			set_max_usb4_cable_speed(port);
 			switch (cable[port].attr.p_rev30.ss) {
 			case USB_R30_SS_U40_GEN3:
 			case USB_R30_SS_U32_U40_GEN1: