Some tcpc device-drivers need to explicitly be told to watch for connection
events, otherwise the tcpc will not generate any TCPM_CC_EVENTs and devices
being plugged into the Type-C port will not be noticed.

For dual-role ports tcpm_start_drp_toggling() is used to tell the tcpc to
watch for connection events. But for single-role ports we've so far been
falling back to just calling tcpm_set_cc(). For some tcpc-s such as the
fusb302 this is not enough and no TCPM_CC_EVENT will be generated.

This commit adds a new start_srp_connection_detect callback to tcpc_dev
and when this is implemented calls this in place of start_drp_toggling
for SRP devices.

Fixes: ea3b4d5523bc("usb: typec: fusb302: Resolve fixed power role ...")
Cc: Adam Thomson <adam.thomson.opensou...@diasemi.com>
Signed-off-by: Hans de Goede <hdego...@redhat.com>
---
 drivers/usb/typec/tcpm/tcpm.c | 8 ++++++++
 include/linux/usb/tcpm.h      | 6 ++++++
 2 files changed, 14 insertions(+)

diff --git a/drivers/usb/typec/tcpm/tcpm.c b/drivers/usb/typec/tcpm/tcpm.c
index a2233d72ae7c..1af54af90b50 100644
--- a/drivers/usb/typec/tcpm/tcpm.c
+++ b/drivers/usb/typec/tcpm/tcpm.c
@@ -2553,6 +2553,14 @@ static bool tcpm_start_drp_toggling(struct tcpm_port 
*port,
                        return true;
        }
 
+       if (port->tcpc->start_srp_connection_detect &&
+           port->port_type != TYPEC_PORT_DRP) {
+               tcpm_log_force(port, "Start SRP connection detection");
+               ret = port->tcpc->start_srp_connection_detect(port->tcpc, cc);
+               if (!ret)
+                       return true;
+       }
+
        return false;
 }
 
diff --git a/include/linux/usb/tcpm.h b/include/linux/usb/tcpm.h
index 0c532ca3f079..bf2bbbf2e2b2 100644
--- a/include/linux/usb/tcpm.h
+++ b/include/linux/usb/tcpm.h
@@ -125,6 +125,10 @@ struct tcpc_config {
  *             Optional; if supported by hardware, called to start DRP
  *             toggling. DRP toggling is stopped automatically if
  *             a connection is established.
+ * @start_srp_connection_detect:
+ *             Optional; if supported by hardware, called to start connection
+ *             detection for single role ports. Connection detection is stopped
+ *             automatically if a connection is established.
  * @try_role:  Optional; called to set a preferred role
  * @pd_transmit:Called to transmit PD message
  * @mux:       Pointer to multiplexer data
@@ -149,6 +153,8 @@ struct tcpc_dev {
                         enum typec_role role, enum typec_data_role data);
        int (*start_drp_toggling)(struct tcpc_dev *dev,
                                  enum typec_cc_status cc);
+       int (*start_srp_connection_detect)(struct tcpc_dev *dev,
+                                          enum typec_cc_status cc);
        int (*try_role)(struct tcpc_dev *dev, int role);
        int (*pd_transmit)(struct tcpc_dev *dev, enum tcpm_transmit_type type,
                           const struct pd_message *msg);
-- 
2.21.0

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