On 5/14/21 10:26 PM, Badhri Jagan Sridharan wrote:
When vbus auto discharge is enabled, TCPCI based TCPC transitions
into Attached.SNK/Attached.SRC state. During PR_SWAP, TCPCI based
TCPC would disconnect when partner changes power roles. TCPC has
to be moved APPLY RC state during PR_SWAP. This is done by
ROLE_CONTROL.CC1 != ROLE_CONTROL.CC2 and
POWER_CONTROL.AutodischargeDisconnect is 0. Once the swap sequence
is done, AutoDischargeDisconnect is re-enabled.
Fixes: f321a02caebd ("usb: typec: tcpm: Implement enabling Auto Discharge disconnect support")
Signed-off-by: Badhri Jagan Sridharan <badhri@xxxxxxxxxx>
---
drivers/usb/typec/tcpm/tcpm.c | 16 ++++++++++++++++
include/linux/usb/tcpm.h | 4 ++++
2 files changed, 20 insertions(+)
diff --git a/drivers/usb/typec/tcpm/tcpm.c b/drivers/usb/typec/tcpm/tcpm.c
index b475d9b9d38d..5bac4978efb3 100644
--- a/drivers/usb/typec/tcpm/tcpm.c
+++ b/drivers/usb/typec/tcpm/tcpm.c
@@ -786,6 +786,19 @@ static int tcpm_enable_auto_vbus_discharge(struct tcpm_port *port, bool enable)
return ret;
}
+static void tcpm_apply_rc(struct tcpm_port *port)
+{
+ /*
+ * TCPCI: Move to APPLY_RC state to prevent disconnect during PR_SWAP
+ * when Vbus auto discharge on disconnect is enabled.
+ */
+ if (port->tcpc->enable_auto_vbus_discharge) {
+ tcpm_log(port, "Apply_RC");
+ port->tcpc->apply_rc(port->tcpc, port->cc_req, port->polarity);
This is called unconditionally. I think you'll need an additional
&& port->tcpc->apply_rc
in the if statement above.
+ tcpm_enable_auto_vbus_discharge(port, false);
+ }
+}
+
/*
* Determine RP value to set based on maximum current supported
* by a port if configured as source.
@@ -4428,6 +4441,7 @@ static void run_state_machine(struct tcpm_port *port)
tcpm_set_state(port, ready_state(port), 0);
break;
case PR_SWAP_START:
+ tcpm_apply_rc(port);
if (port->pwr_role == TYPEC_SOURCE)
tcpm_set_state(port, PR_SWAP_SRC_SNK_TRANSITION_OFF,
PD_T_SRC_TRANSITION);
@@ -4467,6 +4481,7 @@ static void run_state_machine(struct tcpm_port *port)
tcpm_set_state(port, ERROR_RECOVERY, PD_T_PS_SOURCE_ON_PRS);
break;
case PR_SWAP_SRC_SNK_SINK_ON:
+ tcpm_enable_auto_vbus_discharge(port, true);
/* Set the vbus disconnect threshold for implicit contract */
tcpm_set_auto_vbus_discharge_threshold(port, TYPEC_PWR_MODE_USB, false, VSAFE5V);
tcpm_set_state(port, SNK_STARTUP, 0);
@@ -4483,6 +4498,7 @@ static void run_state_machine(struct tcpm_port *port)
PD_T_PS_SOURCE_OFF);
break;
case PR_SWAP_SNK_SRC_SOURCE_ON:
+ tcpm_enable_auto_vbus_discharge(port, true);
tcpm_set_cc(port, tcpm_rp_cc(port));
tcpm_set_vbus(port, true);
/*
diff --git a/include/linux/usb/tcpm.h b/include/linux/usb/tcpm.h
index 42fcfbe10590..bffc8d3e14ad 100644
--- a/include/linux/usb/tcpm.h
+++ b/include/linux/usb/tcpm.h
@@ -66,6 +66,8 @@ enum tcpm_transmit_type {
* For example, some tcpcs may include BC1.2 charger detection
* and use that in this case.
* @set_cc: Called to set value of CC pins
+ * @apply_rc: Optional; Needed to move TCPCI based chipset to APPLY_RC state
+ * as stated by the TCPCI specification.
* @get_cc: Called to read current CC pin values
* @set_polarity:
* Called to set polarity
@@ -120,6 +122,8 @@ struct tcpc_dev {
int (*get_vbus)(struct tcpc_dev *dev);
int (*get_current_limit)(struct tcpc_dev *dev);
int (*set_cc)(struct tcpc_dev *dev, enum typec_cc_status cc);
+ int (*apply_rc)(struct tcpc_dev *dev, enum typec_cc_status cc,
+ enum typec_cc_polarity polarity);
int (*get_cc)(struct tcpc_dev *dev, enum typec_cc_status *cc1,
enum typec_cc_status *cc2);
int (*set_polarity)(struct tcpc_dev *dev,
