[PATCH v3 09/12] usb: typec: tcpm: add state machine support for SRC_VDM_IDENTITY_REQUEST

RD Babiera
2024-01-08T19:16:46Z

Add SRC_VDM_IDENTITY_REQUEST state which first enters after SRC_STARTUP.
The state sends Discover Identity on SOP' and transitions to
SRC_SEND_CAPABILITIES. SRC_SEND_CAPABILITIES will transition back into
SRC_VDM_IDENTITY_REQUEST instead of retrying immediately.

Signed-off-by: RD Babiera <rdbabiera@google.com>
Reviewed-by: Heikki Krogerus <heikki.krogerus@linux.intel.com>
---
Changes since v2:
* Added reviewed-by tag
---
drivers/usb/typec/tcpm/tcpm.c | 49 ++++++++++++++++++++++++++++++-----
1 file changed, 43 insertions(+), 6 deletions(-)

diff --git a/drivers/usb/typec/tcpm/tcpm.c b/drivers/usb/typec/tcpm/tcpm.c
index a870fbc6bc35..1ce525c8f97c 100644
--- a/drivers/usb/typec/tcpm/tcpm.c
+++ b/drivers/usb/typec/tcpm/tcpm.c
@@ -146,7 +146,9 @@
S(PORT_RESET_WAIT_OFF), \
\
S(AMS_START), \
- S(CHUNK_NOT_SUPP)
+ S(CHUNK_NOT_SUPP), \
+ \
+ S(SRC_VDM_IDENTITY_REQUEST)

#define FOREACH_AMS(S) \
S(NONE_AMS), \
@@ -1963,6 +1965,7 @@ static int tcpm_pd_svdm(struct tcpm_port *port, struct typec_altmode *adev,
ret = tcpm_ams_start(port, VCONN_SWAP);
if (!ret)
return 0;
+ /* Cannot perform Vconn swap */
port->upcoming_state = INVALID_STATE;
port->send_discover_prime = false;
}
@@ -1994,6 +1997,16 @@ static int tcpm_pd_svdm(struct tcpm_port *port, struct typec_altmode *adev,
* the svdm_version for the cable moving forward.
*/
svdm_consume_identity_sop_prime(port, p, cnt);
+
+ /*
+ * If received in SRC_VDM_IDENTITY_REQUEST, continue
+ * to SRC_SEND_CAPABILITIES
+ */
+ if (port->state == SRC_VDM_IDENTITY_REQUEST) {
+ tcpm_set_state(port, SRC_SEND_CAPABILITIES, 0);
+ return 0;
+ }
+
*response_tx_sop_type = TCPC_TX_SOP;
response[0] = VDO(USB_SID_PD, 1,
typec_get_negotiated_svdm_version(typec),
@@ -2288,7 +2301,8 @@ static void vdm_run_state_machine(struct tcpm_port *port)
* if there's traffic or we're not in PDO ready state don't send
* a VDM.
*/
- if (port->state != SRC_READY && port->state != SNK_READY) {
+ if (port->state != SRC_READY && port->state != SNK_READY &&
+ port->state != SRC_VDM_IDENTITY_REQUEST) {
port->vdm_sm_running = false;
break;
}
@@ -2364,13 +2378,22 @@ static void vdm_run_state_machine(struct tcpm_port *port)
tcpm_ams_finish(port);
break;
case VDM_STATE_ERR_SEND:
+ /*
+ * When sending Discover Identity to SOP' before establishing an
+ * explicit contract, do not retry. Instead, weave sending
+ * Source_Capabilities over SOP and Discover Identity over SOP'.
+ */
+ if (port->state == SRC_VDM_IDENTITY_REQUEST) {
+ tcpm_ams_finish(port);
+ port->vdm_state = VDM_STATE_DONE;
+ tcpm_set_state(port, SRC_SEND_CAPABILITIES, 0);
/*
* A partner which does not support USB PD will not reply,
* so this is not a fatal error. At the same time, some
* devices may not return GoodCRC under some circumstances,
* so we need to retry.
*/
- if (port->vdm_retries < 3) {
+ } else if (port->vdm_retries < 3) {
tcpm_log(port, "VDM Tx error, retry");
port->vdm_retries++;
port->vdm_state = VDM_STATE_READY;
@@ -4478,8 +4501,12 @@ static void run_state_machine(struct tcpm_port *port)
}
ret = tcpm_pd_send_source_caps(port);
if (ret < 0) {
- tcpm_set_state(port, SRC_SEND_CAPABILITIES,
- PD_T_SEND_SOURCE_CAP);
+ if (tcpm_can_communicate_sop_prime(port) &&
+ IS_ERR_OR_NULL(port->cable))
+ tcpm_set_state(port, SRC_VDM_IDENTITY_REQUEST, 0);
+ else
+ tcpm_set_state(port, SRC_SEND_CAPABILITIES,
+ PD_T_SEND_SOURCE_CAP);
} else {
/*
* Per standard, we should clear the reset counter here.
@@ -5395,6 +5422,15 @@ static void run_state_machine(struct tcpm_port *port)
tcpm_pd_send_control(port, PD_CTRL_NOT_SUPP, TCPC_TX_SOP);
tcpm_set_state(port, port->pwr_role == TYPEC_SOURCE ? SRC_READY : SNK_READY, 0);
break;
+
+ /* Cable states */
+ case SRC_VDM_IDENTITY_REQUEST:
+ port->send_discover_prime = true;
+ port->tx_sop_type = TCPC_TX_SOP_PRIME;
+ mod_send_discover_delayed_work(port, 0);
+ port->upcoming_state = SRC_SEND_CAPABILITIES;
+ break;
+
default:
WARN(1, "Unexpected port state %d\n", port->state);
break;
@@ -6120,7 +6156,8 @@ static void tcpm_send_discover_work(struct kthread_work *work)
}

/* Retry if the port is not idle */
- if ((port->state != SRC_READY && port->state != SNK_READY) || port->vdm_sm_running) {
+ if ((port->state != SRC_READY && port->state != SNK_READY &&
+ port->state != SRC_VDM_IDENTITY_REQUEST) || port->vdm_sm_running) {
mod_send_discover_delayed_work(port, SEND_DISCOVER_RETRY_MS);
goto unlock;
}
--
2.43.0.472.g3155946c3a-goog