TCPMv2: Reset stored PD revs at appropriate times

Stored PD revs for partners should only be reset upon Detach, Hard
Reset, or Error Recovery. Don't do it when the PE enters a Startup
state, e.g. after a Power Role Swap.

BUG=b:173725284,b:179198412
TEST=make buildall
TEST=PR Swap after SOP' Discover Identity with PD 2.0 cable; subsequent
     SOP' messages still PD 2.0; subsequent Enter_USB message has
     correct cable speed
BRANCH=none

Signed-off-by: Abe Levkoy <alevkoy@chromium.org>
Change-Id: I2c12287c99154fba96e4f04a76ebc48273b0bb2e
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/ec/+/2676265
Reviewed-by: Diana Z <dzigterman@chromium.org>
Tested-by: Divya Sasidharan <divya.s.sasidharan@intel.corp-partner.google.com>
Tested-by: Ayushee Shah <ayushee.shah@intel.com>
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/ec/+/2684754

4 files changed, 46 insertions, 5 deletions

diff --git a/common/usbc/usb_pe_drp_sm.c b/common/usbc/usb_pe_drp_sm.c
index 71ff487a69..cc17841da6 100644
--- a/common/usbc/usb_pe_drp_sm.c
+++ b/common/usbc/usb_pe_drp_sm.c
@@ -2167,7 +2167,7 @@ static void pe_src_startup_entry(int port)
 	pe[port].caps_counter = 0;
 
 	/* Reset the protocol layer */
-	prl_reset(port);
+	prl_reset_soft(port);
 
 	/*
 	 * Protocol layer reset clears the message IDs for all SOP types.
@@ -2993,7 +2993,7 @@ static void pe_snk_startup_entry(int port)
 	print_current_state(port);
 
 	/* Reset the protocol layer */
-	prl_reset(port);
+	prl_reset_soft(port);
 
 	/*
 	 * Protocol layer reset clears the message IDs for all SOP types.
diff --git a/common/usbc/usb_prl_sm.c b/common/usbc/usb_prl_sm.c
index 5f1ca8e24c..0affa113b5 100644
--- a/common/usbc/usb_prl_sm.c
+++ b/common/usbc/usb_prl_sm.c
@@ -669,7 +669,8 @@ void prl_send_ext_data_msg(int port,
 }
 #endif /* CONFIG_USB_PD_EXTENDED_MESSAGES */
 
-static void prl_set_default_pd_revision(int port) {
+void prl_set_default_pd_revision(int port)
+{
 	/*
 	 * Initialize to highest revision supported. If the port or cable
 	 * partner doesn't support this revision, the Protocol Engine will
@@ -706,7 +707,6 @@ void prl_run(int port, int evt, int en)
 	case SM_PAUSED:
 		if (!en)
 			break;
-		prl_set_default_pd_revision(port);
 		/* fall through */
 	case SM_INIT:
 		prl_init(port);
@@ -1285,6 +1285,18 @@ static void prl_hr_reset_layer_entry(const int port)
 		tcpm_set_rx_enable(port, 0);
 
 	/*
+	 * PD r3.0 v2.0, ss6.2.1.1.5:
+	 * After a physical or logical (USB Type-C Error Recovery) Attach, a
+	 * Port discovers the common Specification Revision level between itself
+	 * and its Port Partner and/or the Cable Plug(s), and uses this
+	 * Specification Revision level until a Detach, Hard Reset or Error
+	 * Recovery happens.
+	 *
+	 * This covers the Hard Reset case.
+	 */
+	prl_set_default_pd_revision(port);
+
+	/*
 	 * Protocol Layer message transmission transitions to
 	 * PRL_Tx_Wait_For_Message_Request state.
 	 */
diff --git a/common/usbc/usb_tc_drp_acc_trysrc_sm.c b/common/usbc/usb_tc_drp_acc_trysrc_sm.c
index 1d6b9b995f..fab7757e9b 100644
--- a/common/usbc/usb_tc_drp_acc_trysrc_sm.c
+++ b/common/usbc/usb_tc_drp_acc_trysrc_sm.c
@@ -717,6 +717,8 @@ static void tc_detached(int port)
 	tc_pd_connection(port, 0);
 	tcpm_debug_accessory(port, 0);
 	tc_set_modes_exit(port);
+	if (IS_ENABLED(CONFIG_USB_PRL_SM))
+		prl_set_default_pd_revision(port);
 }
 
 static inline void pd_set_dual_role_and_event(int port,
@@ -1455,6 +1457,22 @@ static void restart_tc_sm(int port, enum usb_tc_state start_state)
 		charge_manager_update_dualrole(port, CAP_UNKNOWN);
 	}
 
+	/*
+	 * PD r3.0 v2.0, ss6.2.1.1.5:
+	 * After a physical or logical (USB Type-C Error Recovery) Attach, a
+	 * Port discovers the common Specification Revision level between itself
+	 * and its Port Partner and/or the Cable Plug(s), and uses this
+	 * Specification Revision level until a Detach, Hard Reset or Error
+	 * Recovery happens.
+	 *
+	 * This covers the Error Recovery case, because TC_ERROR_RECOVERY
+	 * reinitializes the TC state machine. This also covers the implicit
+	 * case when PD is suspended and resumed or when the state machine is
+	 * first initialized.
+	 */
+	if (IS_ENABLED(CONFIG_USB_PRL_SM))
+		prl_set_default_pd_revision(port);
+
 #ifdef CONFIG_USB_PE_SM
 	tc_enable_pd(port, 0);
 	tc[port].ps_reset_state = PS_STATE0;
diff --git a/include/usb_prl_sm.h b/include/usb_prl_sm.h
index 6a143f9acc..79b0b9c35c 100644
--- a/include/usb_prl_sm.h
+++ b/include/usb_prl_sm.h
@@ -45,13 +45,24 @@ void prl_set_debug_level(enum debug_level level);
 void prl_reset(int port);
 
 /**
- * Resets the Protocol Layer State Machine (softly)
+ * Resets the Protocol Layer state machine but does not reset the stored PD
+ * revisions of the partners.
  *
  * @param port USB-C port number
  */
 void prl_reset_soft(int port);
 
 /**
+ * resets the stored pd revisions for each sop type to their default value, the
+ * highest revision supported by this implementation. per pd r3.0 v2.0,
+ * ss6.2.1.1.5, this should only happen upon detach, hard reset, or error
+ * recovery.
+ *
+ * @param port USB-C port number
+ */
+void prl_set_default_pd_revision(int port);
+
+/**
  * Runs the Protocol Layer State Machine
  *
  * @param port USB-C port number