[PATCH v3 3/3] usb: typec: tcpm: charge current handling for sink during hard reset

[Badhri Jagan Sridharan]

During the initial connect to a non-pd port, sink would hard reset
twice before deeming that the port partner is non-pd. TCPM sets the
the charge path to false during the hard reset. This causes unnecessary
connects/disconnects of charge path and makes port take longer to
charge from the non-pd ports. Avoid this by not setting the charge path
to false unless the partner has already identified to be pd capable.

When partner is a pd port, set the charge path to false in
SNK_HARD_RESET_SINK_OFF. Set the current limits to default value based
of CC pull up and resume the charge path when port enters
SNK_HARD_RESET_SINK_ON.

Signed-off-by: Badhri Jagan Sridharan <badhri@xxxxxxxxxx>

--------
Changes in V3:
Rebase on top of usb-next

Changes in V2:
Based on feedback of jackp@xxxxxxxxxxxxxx
- vsafe_5v_hard_reset flag from tcpc_config is removed
- Patch only differentiates between pd port partner and non-pd port
partner

V1 version of the patch is here:
https://lkml.org/lkml/2018/9/14/11
---
 drivers/usb/typec/tcpm/tcpm.c | 9 ++++++++-
 1 file changed, 8 insertions(+), 1 deletion(-)

diff --git a/drivers/usb/typec/tcpm/tcpm.c b/drivers/usb/typec/tcpm/tcpm.c
index c3ac0e46106b..c25a69922ee6 100644
--- a/drivers/usb/typec/tcpm/tcpm.c
+++ b/drivers/usb/typec/tcpm/tcpm.c
@@ -3273,7 +3273,8 @@ static void run_state_machine(struct tcpm_port *port)
 	case SNK_HARD_RESET_SINK_OFF:
 		memset(&port->pps_data, 0, sizeof(port->pps_data));
 		tcpm_set_vconn(port, false);
-		tcpm_set_charge(port, false);
+		if (port->pd_capable)
+			tcpm_set_charge(port, false);
 		tcpm_set_roles(port, port->self_powered, TYPEC_SINK,
 			       TYPEC_DEVICE);
 		/*
@@ -3305,6 +3306,12 @@ static void run_state_machine(struct tcpm_port *port)
 		 * Similar, dual-mode ports in source mode should transition
 		 * to PE_SNK_Transition_to_default.
 		 */
+		if (port->pd_capable) {
+			tcpm_set_current_limit(port,
+					       tcpm_get_current_limit(port),
+					       5000);
+			tcpm_set_charge(port, true);
+		}
 		tcpm_set_attached_state(port, true);
 		tcpm_set_state(port, SNK_STARTUP, 0);
 		break;
-- 
2.19.0.605.g01d371f741-goog