Re: [PATCH v1 3/4] usb: typec: tcpm: Move TCPC to APPLY_RC state during PR_SWAP

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@google.com

---

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,