[PATCH 0/5] usb: typec: cable comms on RT1711H-compatible TCPCs and FUSB302

[PATCH 0/5] usb: typec: cable comms on RT1711H-compatible TCPCs and FUSB302

[Alexey Charkov]

Neither the RT1711H family (including the HUSB311 and ET7304) nor the
FUSB302 lets TCPM talk to cable plugs today, so cable discovery is
skipped, and with it the cable's current and speed ratings.

The RT1711H family handles SOP' like any other TCPCI-compliant TCPC, but
enabling it exposed a problem in the TCPCI core: it set SOP' in
RECEIVE_DETECT whenever the TCPC can talk to cables, regardless of who
sources VCONN. With the partner as the VCONN Source, the port then acks
and processes the partner's own traffic with the cable plug.

Patch 1 fixes a TCPM bug that cable communication on the FUSB302 made
visible: after a VCONN swap, a source resets the cable plug twice.
Patch 2 lets a TCPCI TCPC receive SOP' only while it sources VCONN,
which also affects the Maxim TCPCs, the only ones that enable SOP'
today. Patch 3 enables SOP' on the RT1711H family. Patches 4 and 5 add
SOP' to the FUSB302 driver, receiving it under the same VCONN rule.

Tested on an RK3576 EVB1 (HUSB311, source-only) and Flipper One boards
(FUSB302B):
- Without patch 2, a FUSB302 sink sent SOP' Discover Identity over a
  cable with no e-marker, so the HUSB311 had no VCONN to source. The
  HUSB311 acked each one and its TCPM answered over SOP, after which the
  sink soft reset the contract every time.
- With patch 2, the same messages went unacked and the HUSB311 port
  correctly ignored them.
- Over an e-marked 5A EPR cable, the HUSB311 sourced VCONN, read the
  cable identity and completed discovery, while the FUSB302 sink kept
  SOP' reception off.
- With a FUSB302 as source on the same cable, it sourced VCONN, read
  the cable identity and completed discovery. The cable plug accepted
  the FUSB302's automatic GoodCRC to its replies, which the datasheet
  leaves undocumented for SOP'.
- Between two FUSB302 ports on the same cable, VCONN swaps both ways
  moved SOP' reception along with VCONN, and each new VCONN Source
  soft reset the cable plug over SOP'. Without patch 1, the source did
  so twice.

Signed-off-by: Alexey Charkov <alchark@flipper.net>
---
Alexey Charkov (5):
      usb: typec: tcpm: Stop a source from repeating a cable Soft_Reset
      usb: typec: tcpci: Receive SOP' only while sourcing VCONN
      usb: typec: tcpci_rt1711h: Enable SOP' communication
      usb: typec: fusb302: Tell SOP' messages apart from SOP
      usb: typec: fusb302: Enable SOP' communication

 drivers/usb/typec/tcpm/fusb302.c       | 63 ++++++++++++++++++++++++++---
 drivers/usb/typec/tcpm/fusb302_reg.h   | 10 +++++
 drivers/usb/typec/tcpm/tcpci.c         | 72 +++++++++++++++++++++++-----------
 drivers/usb/typec/tcpm/tcpci_rt1711h.c |  1 +
 drivers/usb/typec/tcpm/tcpm.c          |  2 +
 5 files changed, 119 insertions(+), 29 deletions(-)
---
base-commit: 2637bdec0535a2044cd830eba9a79363651d9043
change-id: 20261103-husb311-cable-comm-46f2e77e4c18

Best regards,
--  
Alexey Charkov <alchark@flipper.net>

[PATCH 1/5] usb: typec: tcpm: Stop a source from repeating a cable Soft_Reset

[Alexey Charkov]

A soft reset AMS starts with upcoming_state set to SOFT_RESET_SEND and a
call to tcpm_ams_start(). A sink then enters SOFT_RESET_SEND through
upcoming_state, which consumes it. A source enters SOFT_RESET_SEND right
away and leaves upcoming_state set, for the next SRC_READY to replay.

After an SOP Soft_Reset that is harmless, as the Accept handler or a
hard reset replaces upcoming_state. The SOP' Soft_Reset sent after a
VCONN swap returns to SRC_READY instead, so a source resets the cable
plug a second time, outside of any AMS.

Clear upcoming_state when a source enters SOFT_RESET_SEND right away.

Cc: stable@vger.kernel.org
Fixes: 6bd181ba60e1 ("usb: typec: tcpm: add control message support to sop'")
Signed-off-by: Alexey Charkov <alchark@flipper.net>
---
 drivers/usb/typec/tcpm/tcpm.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/drivers/usb/typec/tcpm/tcpm.c b/drivers/usb/typec/tcpm/tcpm.c
index d721baef5210..c0c54caf99d6 100644
--- a/drivers/usb/typec/tcpm/tcpm.c
+++ b/drivers/usb/typec/tcpm/tcpm.c
@@ -1914,6 +1914,8 @@ static int tcpm_ams_start(struct tcpm_port *port, enum tcpm_ams ams)
 		} else if (ams == SOFT_RESET_AMS) {
 			if (!port->explicit_contract)
 				tcpm_set_cc(port, tcpm_rp_cc(port));
+			/* entered right away, so don't leave it to be replayed */
+			port->upcoming_state = INVALID_STATE;
 			tcpm_set_state(port, SOFT_RESET_SEND, 0);
 			return ret;
 		} else if (tcpm_vdm_ams(port)) {

-- 
2.56.0

Re: [PATCH 1/5] usb: typec: tcpm: Stop a source from repeating a cable Soft_Reset

[sashiko-bot]

> A soft reset AMS starts with upcoming_state set to SOFT_RESET_SEND and a
> call to tcpm_ams_start(). A sink then enters SOFT_RESET_SEND through
> upcoming_state, which consumes it. A source enters SOFT_RESET_SEND right
> away and leaves upcoming_state set, for the next SRC_READY to replay.
> 
> After an SOP Soft_Reset that is harmless, as the Accept handler or a
> hard reset replaces upcoming_state. The SOP' Soft_Reset sent after a
> VCONN swap returns to SRC_READY instead, so a source resets the cable
> plug a second time, outside of any AMS.
> 
> Clear upcoming_state when a source enters SOFT_RESET_SEND right away.
> 
> Cc: stable@vger.kernel.org
> Fixes: 6bd181ba60e1 ("usb: typec: tcpm: add control message support to sop'")
> Signed-off-by: Alexey Charkov <alchark@flipper.net>

Sashiko has reviewed this patch and found no issues.

-- 
Sashiko AI review · https://sashiko.dev/#/patchset/20261103-husb311-cable-comm-v1-0-6217dabc1a85@flipper.net?part=1

[PATCH 2/5] usb: typec: tcpci: Receive SOP' only while sourcing VCONN

[Alexey Charkov]

A TCPC acks every message type enabled in RECEIVE_DETECT and passes it
on to TCPM. With SOP' enabled while the partner sources VCONN, the port
acks the partner's requests to the cable plug and the plug's replies to
the partner, colliding with the GoodCRC that the plug or the partner
sends. TCPM also tries to answer these messages as if they were destined
to it, which for the case of a partner's SOP' Discover Identity on a
HUSB311 made the partner soft reset the contract every time.

TCPM talks to the cable plug only while it is the VCONN Source, as USB
PD 3.0 section 6.3.11 requires, so listen for SOP' only then.

Switch SOP' reception off before VCONN goes off and on only once it is
on. If that fails, warn instead of failing the VCONN switch: SOP'
reception left off only costs cable discovery, and left on is no worse
than before this change.

Cc: stable@vger.kernel.org
Fixes: 3bbb9ba4f660 ("usb: typec: tcpci: add tcpm_transmit_type to tcpm_pd_receive")
Signed-off-by: Alexey Charkov <alchark@flipper.net>
---
 drivers/usb/typec/tcpm/tcpci.c | 72 ++++++++++++++++++++++++++++--------------
 1 file changed, 49 insertions(+), 23 deletions(-)

diff --git a/drivers/usb/typec/tcpm/tcpci.c b/drivers/usb/typec/tcpm/tcpci.c
index 6717ac914c6a..af8db6b4497a 100644
--- a/drivers/usb/typec/tcpm/tcpci.c
+++ b/drivers/usb/typec/tcpm/tcpci.c
@@ -41,6 +41,7 @@ struct tcpci {
 	unsigned int rx_type_mask;
 
 	bool controls_vbus;
+	bool vconn_enabled;
 
 	struct tcpc_dev tcpc;
 	struct tcpci_data *data;
@@ -344,11 +345,45 @@ static void tcpci_set_partner_usb_comm_capable(struct tcpc_dev *tcpc, bool capab
 		tcpci->data->set_partner_usb_comm_capable(tcpci, tcpci->data, capable);
 }
 
+static int tcpci_set_pd_rx(struct tcpc_dev *tcpc, bool enable)
+{
+	struct tcpci *tcpci = tcpc_to_tcpci(tcpc);
+	unsigned int reg = 0;
+	int ret;
+
+	if (enable) {
+		reg = TCPC_RX_DETECT_SOP | TCPC_RX_DETECT_HARD_RESET;
+		/* Only the VCONN Source talks to the cable plug */
+		if (tcpci->data->cable_comm_capable && tcpci->vconn_enabled)
+			reg |= TCPC_RX_DETECT_SOP1;
+	}
+
+	tcpci->rx_type_mask = reg;
+	ret = regmap_write(tcpci->regmap, TCPC_RX_DETECT, reg);
+	if (ret < 0)
+		return ret;
+
+	return 0;
+}
+
 static int tcpci_set_vconn(struct tcpc_dev *tcpc, bool enable)
 {
 	struct tcpci *tcpci = tcpc_to_tcpci(tcpc);
 	int ret;
 
+	/*
+	 * Without VCONN from us, SOP' traffic is between the partner and the
+	 * cable plug, and our GoodCRC would collide with theirs. So stop
+	 * receiving SOP' before VCONN goes off, and start only once it is on.
+	 * Neither is worth failing the VCONN switch over.
+	 */
+	if (!enable) {
+		tcpci->vconn_enabled = false;
+		if ((tcpci->rx_type_mask & TCPC_RX_DETECT_SOP1) &&
+		    tcpci_set_pd_rx(tcpc, true) < 0)
+			dev_warn(tcpci->dev, "Failed to disable SOP' reception\n");
+	}
+
 	/* Handle vendor set vconn */
 	if (tcpci->data->set_vconn) {
 		ret = tcpci->data->set_vconn(tcpci, tcpci->data, enable);
@@ -356,9 +391,20 @@ static int tcpci_set_vconn(struct tcpc_dev *tcpc, bool enable)
 			return ret;
 	}
 
-	return regmap_update_bits(tcpci->regmap, TCPC_POWER_CTRL,
-				TCPC_POWER_CTRL_VCONN_ENABLE,
-				enable ? TCPC_POWER_CTRL_VCONN_ENABLE : 0);
+	ret = regmap_update_bits(tcpci->regmap, TCPC_POWER_CTRL,
+				 TCPC_POWER_CTRL_VCONN_ENABLE,
+				 enable ? TCPC_POWER_CTRL_VCONN_ENABLE : 0);
+	if (ret < 0)
+		return ret;
+
+	if (enable) {
+		tcpci->vconn_enabled = true;
+		if (tcpci->data->cable_comm_capable && tcpci->rx_type_mask &&
+		    tcpci_set_pd_rx(tcpc, true) < 0)
+			dev_warn(tcpci->dev, "Failed to enable SOP' reception\n");
+	}
+
+	return 0;
 }
 
 static int tcpci_enable_auto_vbus_discharge(struct tcpc_dev *dev, bool enable)
@@ -478,26 +524,6 @@ static int tcpci_set_roles(struct tcpc_dev *tcpc, bool attached,
 	return 0;
 }
 
-static int tcpci_set_pd_rx(struct tcpc_dev *tcpc, bool enable)
-{
-	struct tcpci *tcpci = tcpc_to_tcpci(tcpc);
-	unsigned int reg = 0;
-	int ret;
-
-	if (enable) {
-		reg = TCPC_RX_DETECT_SOP | TCPC_RX_DETECT_HARD_RESET;
-		if (tcpci->data->cable_comm_capable)
-			reg |= TCPC_RX_DETECT_SOP1;
-	}
-
-	tcpci->rx_type_mask = reg;
-	ret = regmap_write(tcpci->regmap, TCPC_RX_DETECT, reg);
-	if (ret < 0)
-		return ret;
-
-	return 0;
-}
-
 static int tcpci_get_vbus(struct tcpc_dev *tcpc)
 {
 	struct tcpci *tcpci = tcpc_to_tcpci(tcpc);

-- 
2.56.0

Re: [PATCH 2/5] usb: typec: tcpci: Receive SOP' only while sourcing VCONN

[sashiko-bot]

> A TCPC acks every message type enabled in RECEIVE_DETECT and passes it
> on to TCPM. With SOP' enabled while the partner sources VCONN, the port
> acks the partner's requests to the cable plug and the plug's replies to
> the partner, colliding with the GoodCRC that the plug or the partner
> sends. TCPM also tries to answer these messages as if they were destined
> to it, which for the case of a partner's SOP' Discover Identity on a
> HUSB311 made the partner soft reset the contract every time.
> 
> TCPM talks to the cable plug only while it is the VCONN Source, as USB
> PD 3.0 section 6.3.11 requires, so listen for SOP' only then.
> 
> Switch SOP' reception off before VCONN goes off and on only once it is
> on. If that fails, warn instead of failing the VCONN switch: SOP'
> reception left off only costs cable discovery, and left on is no worse
> than before this change.
> 
> Cc: stable@vger.kernel.org
> Fixes: 3bbb9ba4f660 ("usb: typec: tcpci: add tcpm_transmit_type to tcpm_pd_receive")
> Signed-off-by: Alexey Charkov <alchark@flipper.net>

Sashiko has reviewed this patch and found no issues.

-- 
Sashiko AI review · https://sashiko.dev/#/patchset/20261103-husb311-cable-comm-v1-0-6217dabc1a85@flipper.net?part=2

[PATCH 3/5] usb: typec: tcpci_rt1711h: Enable SOP' communication

[Alexey Charkov]

These TCPCs transmit and receive SOP' as the TCPCI specification
defines, so let TCPM discover e-marked cables through them and learn
their current and speed ratings.

Tested on a HUSB311 with an e-marked 5A EPR cable.

Signed-off-by: Alexey Charkov <alchark@flipper.net>
---
 drivers/usb/typec/tcpm/tcpci_rt1711h.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/drivers/usb/typec/tcpm/tcpci_rt1711h.c b/drivers/usb/typec/tcpm/tcpci_rt1711h.c
index af8356df6b98..232eb721fb3d 100644
--- a/drivers/usb/typec/tcpm/tcpci_rt1711h.c
+++ b/drivers/usb/typec/tcpm/tcpci_rt1711h.c
@@ -337,6 +337,7 @@ static int rt1711h_probe(struct i2c_client *client)
 	chip->data.set_vbus = rt1711h_set_vbus;
 	chip->data.set_vconn = rt1711h_set_vconn;
 	chip->data.start_drp_toggling = rt1711h_start_drp_toggling;
+	chip->data.cable_comm_capable = true;
 	chip->tcpci = tcpci_register_port(chip->dev, &chip->data);
 	if (IS_ERR_OR_NULL(chip->tcpci))
 		return PTR_ERR(chip->tcpci);

-- 
2.56.0

Re: [PATCH 3/5] usb: typec: tcpci_rt1711h: Enable SOP' communication

[sashiko-bot]

> These TCPCs transmit and receive SOP' as the TCPCI specification
> defines, so let TCPM discover e-marked cables through them and learn
> their current and speed ratings.
> 
> Tested on a HUSB311 with an e-marked 5A EPR cable.
> 
> Signed-off-by: Alexey Charkov <alchark@flipper.net>

Sashiko has reviewed this patch and found no issues.

-- 
Sashiko AI review · https://sashiko.dev/#/patchset/20261103-husb311-cable-comm-v1-0-6217dabc1a85@flipper.net?part=3

[PATCH 4/5] usb: typec: fusb302: Tell SOP' messages apart from SOP

[Alexey Charkov]

The driver sends every message with the SOP ordered set and reports
every received one as SOP, which leaves TCPM no way to reach the cable
plug. Start a message with the SOP' ordered set when TCPM asks for it,
and report a received message as SOP' when its RX FIFO token says so.

SOP' is Sync-1, Sync-1, Sync-3, Sync-3 in USB PD. The Sync-3 TX token
and the RX FIFO token codes are from the token tables of the FUSB302B
datasheet.

Nothing changes yet: TCPM asks for SOP' only from a port that claims
cable communication, and the chip drops SOP' packets until ENSOP1 is
set.

Signed-off-by: Alexey Charkov <alchark@flipper.net>
---
 drivers/usb/typec/tcpm/fusb302.c     | 26 ++++++++++++++++++++------
 drivers/usb/typec/tcpm/fusb302_reg.h | 10 ++++++++++
 2 files changed, 30 insertions(+), 6 deletions(-)

diff --git a/drivers/usb/typec/tcpm/fusb302.c b/drivers/usb/typec/tcpm/fusb302.c
index 3319f6a2b0c9..8b3a2e095ef8 100644
--- a/drivers/usb/typec/tcpm/fusb302.c
+++ b/drivers/usb/typec/tcpm/fusb302.c
@@ -961,7 +961,20 @@ static int tcpm_start_toggling(struct tcpc_dev *dev,
 	return ret;
 }
 
+/* K-codes of the ordered set that starts each kind of packet */
+static const u8 fusb302_sop_tokens[][4] = {
+	[TCPC_TX_SOP] = {
+		FUSB302_TKN_SYNC1, FUSB302_TKN_SYNC1,
+		FUSB302_TKN_SYNC1, FUSB302_TKN_SYNC2,
+	},
+	[TCPC_TX_SOP_PRIME] = {
+		FUSB302_TKN_SYNC1, FUSB302_TKN_SYNC1,
+		FUSB302_TKN_SYNC3, FUSB302_TKN_SYNC3,
+	},
+};
+
 static int fusb302_pd_send_message(struct fusb302_chip *chip,
+				   enum tcpm_transmit_type type,
 				   const struct pd_message *msg)
 {
 	int ret = 0;
@@ -969,11 +982,9 @@ static int fusb302_pd_send_message(struct fusb302_chip *chip,
 	u8 pos = 0;
 	int len;
 
-	/* SOP tokens */
-	buf[pos++] = FUSB302_TKN_SYNC1;
-	buf[pos++] = FUSB302_TKN_SYNC1;
-	buf[pos++] = FUSB302_TKN_SYNC1;
-	buf[pos++] = FUSB302_TKN_SYNC2;
+	memcpy(&buf[pos], fusb302_sop_tokens[type],
+	       sizeof(fusb302_sop_tokens[type]));
+	pos += sizeof(fusb302_sop_tokens[type]);
 
 	len = pd_header_cnt_le(msg->header) * 4;
 	/* plug 2 for header */
@@ -1037,6 +1048,7 @@ static int tcpm_pd_transmit(struct tcpc_dev *dev, enum tcpm_transmit_type type,
 	mutex_lock(&chip->lock);
 	switch (type) {
 	case TCPC_TX_SOP:
+	case TCPC_TX_SOP_PRIME:
 		/* nRetryCount 3 in P2.0 spec, whereas 2 in PD3.0 spec */
 		ret = fusb302_enable_tx_auto_retries(chip, negotiated_rev > PD_REV20 ?
 						     FUSB_REG_CONTROL3_N_RETRIES_2 :
@@ -1044,7 +1056,7 @@ static int tcpm_pd_transmit(struct tcpc_dev *dev, enum tcpm_transmit_type type,
 		if (ret < 0)
 			fusb302_log(chip, "Cannot update retry count ret=%d", ret);
 
-		ret = fusb302_pd_send_message(chip, msg);
+		ret = fusb302_pd_send_message(chip, type, msg);
 		if (ret < 0)
 			fusb302_log(chip,
 				    "cannot send PD message, ret=%d", ret);
@@ -1475,6 +1487,8 @@ static int fusb302_pd_read_message(struct fusb302_chip *chip,
 	 */
 	if ((!len) && (pd_header_type_le(msg->header) == PD_CTRL_GOOD_CRC))
 		tcpm_pd_transmit_complete(chip->tcpm_port, TCPC_TX_SUCCESS);
+	else if ((token & FUSB302_RX_TKN_MASK) == FUSB302_RX_TKN_SOP1)
+		tcpm_pd_receive(chip->tcpm_port, msg, TCPC_TX_SOP_PRIME);
 	else
 		tcpm_pd_receive(chip->tcpm_port, msg, TCPC_TX_SOP);
 
diff --git a/drivers/usb/typec/tcpm/fusb302_reg.h b/drivers/usb/typec/tcpm/fusb302_reg.h
index edc0e4b0f1e6..c98a502bfbfc 100644
--- a/drivers/usb/typec/tcpm/fusb302_reg.h
+++ b/drivers/usb/typec/tcpm/fusb302_reg.h
@@ -174,4 +174,14 @@ enum fusb302_txfifo_tokens {
 	FUSB302_TKN_TXOFF = 0xFE,
 };
 
+/* Tokens starting each packet in the FUSB302 RX FIFO, valid under the mask */
+#define FUSB302_RX_TKN_MASK			GENMASK(7, 5)
+enum fusb302_rxfifo_tokens {
+	FUSB302_RX_TKN_SOP2DB = 0x60,
+	FUSB302_RX_TKN_SOP1DB = 0x80,
+	FUSB302_RX_TKN_SOP2 = 0xA0,
+	FUSB302_RX_TKN_SOP1 = 0xC0,
+	FUSB302_RX_TKN_SOP = 0xE0,
+};
+
 #endif

-- 
2.56.0

Re: [PATCH 4/5] usb: typec: fusb302: Tell SOP' messages apart from SOP

[sashiko-bot]

> The driver sends every message with the SOP ordered set and reports
> every received one as SOP, which leaves TCPM no way to reach the cable
> plug. Start a message with the SOP' ordered set when TCPM asks for it,
> and report a received message as SOP' when its RX FIFO token says so.
> 
> SOP' is Sync-1, Sync-1, Sync-3, Sync-3 in USB PD. The Sync-3 TX token
> and the RX FIFO token codes are from the token tables of the FUSB302B
> datasheet.
> 
> Nothing changes yet: TCPM asks for SOP' only from a port that claims
> cable communication, and the chip drops SOP' packets until ENSOP1 is
> set.
> 
> Signed-off-by: Alexey Charkov <alchark@flipper.net>

Sashiko has reviewed this patch and found no issues.

-- 
Sashiko AI review · https://sashiko.dev/#/patchset/20261103-husb311-cable-comm-v1-0-6217dabc1a85@flipper.net?part=4

[PATCH 5/5] usb: typec: fusb302: Enable SOP' communication

[Alexey Charkov]

Let TCPM discover e-marked cables through the FUSB302 and learn their
current and speed ratings.

Receive SOP' only while sourcing VCONN with PD reception on. Only the
VCONN Source talks to the cable plug, and acking the traffic between the
partner and the plug would collide with their own GoodCRC.

Switch SOP' reception off before VCONN or PD reception goes off and on
only once both are on. If that fails, log it instead of failing the
switch TCPM asked for: SOP' reception left off only costs cable
discovery, and left on with VCONN off makes the port ack the partner's
traffic with the cable plug until PD reception goes off, which beats
keeping VCONN or PD reception in a state TCPM did not request.

Tested on a FUSB302B as source with an e-marked 5A EPR cable. The
datasheet documents the auto-GoodCRC header bits for SOP only, but the
cable plug took the chip's acks to its SOP' replies without retrying.

Signed-off-by: Alexey Charkov <alchark@flipper.net>
---
 drivers/usb/typec/tcpm/fusb302.c | 37 +++++++++++++++++++++++++++++++++++++
 1 file changed, 37 insertions(+)

diff --git a/drivers/usb/typec/tcpm/fusb302.c b/drivers/usb/typec/tcpm/fusb302.c
index 8b3a2e095ef8..10f2dabf3318 100644
--- a/drivers/usb/typec/tcpm/fusb302.c
+++ b/drivers/usb/typec/tcpm/fusb302.c
@@ -725,6 +725,27 @@ static int tcpm_set_polarity(struct tcpc_dev *dev,
 	return 0;
 }
 
+/*
+ * Without VCONN from us, SOP' traffic is between the partner and the cable
+ * plug, and our GoodCRC would collide with theirs. So stop receiving SOP'
+ * before VCONN or PD reception goes off, and start only once both are on.
+ * Neither is worth failing the VCONN or PD reception switch over.
+ */
+static void fusb302_pd_set_sop_prime(struct fusb302_chip *chip, bool on)
+{
+	int ret;
+
+	if (on)
+		ret = fusb302_i2c_set_bits(chip, FUSB_REG_CONTROL1,
+					   FUSB_REG_CONTROL1_ENSOP1);
+	else
+		ret = fusb302_i2c_clear_bits(chip, FUSB_REG_CONTROL1,
+					     FUSB_REG_CONTROL1_ENSOP1);
+	if (ret < 0)
+		fusb302_log(chip, "cannot turn SOP' rx %s, ret=%d",
+			    str_on_off(on), ret);
+}
+
 static int tcpm_set_vconn(struct tcpc_dev *dev, bool on)
 {
 	struct fusb302_chip *chip = container_of(dev, struct fusb302_chip,
@@ -743,6 +764,8 @@ static int tcpm_set_vconn(struct tcpc_dev *dev, bool on)
 		switches0_data = (chip->cc_polarity == TYPEC_POLARITY_CC1) ?
 				 FUSB_REG_SWITCHES0_VCONN_CC2 :
 				 FUSB_REG_SWITCHES0_VCONN_CC1;
+	} else {
+		fusb302_pd_set_sop_prime(chip, false);
 	}
 	ret = fusb302_i2c_mask_write(chip, FUSB_REG_SWITCHES0,
 				     switches0_mask, switches0_data);
@@ -750,6 +773,9 @@ static int tcpm_set_vconn(struct tcpc_dev *dev, bool on)
 		goto done;
 	chip->vconn_on = on;
 	fusb302_log(chip, "vconn := %s", str_on_off(on));
+
+	if (on && chip->pd_rx_on)
+		fusb302_pd_set_sop_prime(chip, true);
 done:
 	mutex_unlock(&chip->lock);
 
@@ -848,6 +874,8 @@ static int tcpm_set_pd_rx(struct tcpc_dev *dev, bool on)
 		goto done;
 	}
 
+	if (!on)
+		fusb302_pd_set_sop_prime(chip, false);
 	ret = fusb302_pd_rx_flush(chip);
 	if (ret < 0) {
 		fusb302_log(chip, "cannot flush pd rx buffer, ret=%d", ret);
@@ -873,6 +901,9 @@ static int tcpm_set_pd_rx(struct tcpc_dev *dev, bool on)
 
 	chip->pd_rx_on = on;
 	fusb302_log(chip, "pd := %s", str_on_off(on));
+
+	if (on && chip->vconn_on)
+		fusb302_pd_set_sop_prime(chip, true);
 done:
 	mutex_unlock(&chip->lock);
 
@@ -1136,6 +1167,11 @@ static void fusb302_bc_lvl_handler_work(struct work_struct *work)
 	mutex_unlock(&chip->lock);
 }
 
+static bool tcpm_cable_comm_capable(struct tcpc_dev *dev)
+{
+	return true;
+}
+
 static void init_tcpc_dev(struct tcpc_dev *fusb302_tcpc_dev)
 {
 	fusb302_tcpc_dev->init = tcpm_init;
@@ -1150,6 +1186,7 @@ static void init_tcpc_dev(struct tcpc_dev *fusb302_tcpc_dev)
 	fusb302_tcpc_dev->set_roles = tcpm_set_roles;
 	fusb302_tcpc_dev->start_toggling = tcpm_start_toggling;
 	fusb302_tcpc_dev->pd_transmit = tcpm_pd_transmit;
+	fusb302_tcpc_dev->cable_comm_capable = tcpm_cable_comm_capable;
 }
 
 static const char * const cc_polarity_name[] = {

-- 
2.56.0

Re: [PATCH 5/5] usb: typec: fusb302: Enable SOP' communication

[sashiko-bot]

> Let TCPM discover e-marked cables through the FUSB302 and learn their
> current and speed ratings.
> 
> Receive SOP' only while sourcing VCONN with PD reception on. Only the
> VCONN Source talks to the cable plug, and acking the traffic between the
> partner and the plug would collide with their own GoodCRC.
> 
> Switch SOP' reception off before VCONN or PD reception goes off and on
> only once both are on. If that fails, log it instead of failing the
> switch TCPM asked for: SOP' reception left off only costs cable
> discovery, and left on with VCONN off makes the port ack the partner's
> traffic with the cable plug until PD reception goes off, which beats
> keeping VCONN or PD reception in a state TCPM did not request.
> 
> Tested on a FUSB302B as source with an e-marked 5A EPR cable. The
> datasheet documents the auto-GoodCRC header bits for SOP only, but the
> cable plug took the chip's acks to its SOP' replies without retrying.
> 
> Signed-off-by: Alexey Charkov <alchark@flipper.net>

Sashiko has reviewed this patch and found no issues.

-- 
Sashiko AI review · https://sashiko.dev/#/patchset/20261103-husb311-cable-comm-v1-0-6217dabc1a85@flipper.net?part=5